This file contains the documentation for Patcher version 3.11, an XEmacs package for automating the maintenance of archive-based projects.

Copyright © 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010 Didier Verna.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled ``Copying'' and ``GNU General Public License'' are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Free Software Foundation.

Patcher
*******

Patcher is an XEmacs package designed to automate and ease the maintenance of archive-based projects. It provides assistance in building, reporting and committing patches, as well as in handling the corresponding ChangeLog entries, for example by creating skeletons.

This info file documents Patcher version 3.11.

Patcher is developed by Didier Verna didier@xemacs.org.

Copying
*******

Patcher is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2, as published by the Software Foundation.

Patcher is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Introduction
************

When a project becomes important in size, or when the development is performed cooperatively by several people across the Internet, it is a common practice to help maintaining it by using a development control system. Such tools (Git, Mercurial, Subversion, Darcs, CVS, PRCS to name a few) usually work by maintaining a centralized or distributed project archive (also called a repository) that keeps track of the history of the changes, lets you develop different ``branches'' at the same time and perform operations like merges between these different project branches.

In such ``archive-based'' maintenance models, making the project evolve usually involves repeatedly the same few steps, some of which can be tedious: you work on your local copy of the project; once you're satisfied with your changes, you create a patch by diffing your local copy against the project's archive; then (or progressively), you construct the ChangeLog entries. Finally, you propose your changes by sending a mail to the developers list with your patch and the ChangeLog entries included, hoping that your proposition will be accepted. If you're one of the maintainers, you will still probably send the message to the list, simply announcing the modification, and immediately commit the patch with an informative log message.

Patcher is an XEmacs package designed to automate this process. Patcher can't work on the project for you. However, as soon as you give it some basic knowledge on the project structure and repository, it can automatically build a patch by comparing your local copy with the repository, create ChangeLog entries, prepare a mail announcing the changes, and even commit the patch for you with a informative log message. All of this is done in just a few keystrokes. Additionally, Patcher can perform some sanity checks, like verifying that your local copy is up-to-date, that you did not forget some ChangeLog entries, that the commit operation went well and so on.

If you're brave and impatient, and want to start using the basics of Patcher as soon as possible, see Quick Start. It is recommended to read it anyway, since it gives an overview of how Patcher works. If you know the basics and want a more detailed guide, see User Manual.

Enjoy using Patcher !

Installation
************

Distribution
============

Patcher is available either as a standalone package, or as part of the standard xemacs-devel XEmacs package.

You can get xemacs-devel in three different ways:

  * You can install xemacs-devel from within XEmacs via the package user interface (accessible from the Tools menu or via M-x list-packages).

  * You can also download the xemacs-devel-<version>-pkg.tar.gz tarball from ftp://ftp.xemacs.org/pub/xemacs/packages/, and unpack it where you put the other packages.

  * xemacs-devel sources are available from the XEmacs CVS repository. The module name is xemacs-devel. See http://www.xemacs.org/Develop/cvsaccess.html for more information about the XEmacs CVS repository.

I also provide Patcher as a standalone package. This is mainly for my personal usage (when developing and debugging new versions) but you might want to use it if you're not interested in the rest of xemacs-devel. The standalone version of Patcher can be found at http://www.lrde.epita.fr/~didier/software/xemacs.php. You will also find different inlined versions of this documentation at that place. For installation instructions, please read the INSTALL file.

Requirements
============

Patcher currently works only with XEmacs 21.4 or later. I'm not sure it works with earlier versions of XEmacs, but I'm sure it does not work with GNU Emacs (see below).

Patcher might also have some other requirements, depending on how you use it:

  * If you let Patcher create ChangeLogs for you (see ChangeLogs Handling), you will need the add-log library from the xemacs-base package, version 2.21 or later, installed on your system. That's actually the may reason for Patcher not being able to run in GNU Emacs, though I have not tried to port it yet.

  * If you want to send mails from Patcher (see Mail Methods), you will need a mail user agent. Patcher currently supports sendmail, message and Gnus natively and through the compose-mail interface. Other MUA might be partly supported when used with compose-mail. Patcher will probably suffer from non critical deficiencies in that case however (it will issue warnings).

Insinuation
===========

With a proper installation of Patcher (either way), you don't need any special trickery in your .emacs file because all entry points to the library should be autoloaded.

However, Patcher has the ability to hook into external libraries, but won't do so unless requested. Currently, Patcher has hooks for Gnus only. If you're using Gnus as your MUA, you might want to add the following line to your gnusrc file:

     (patcher-insinuate-gnus)

This will add some facilities described along the text.

Quick Start
***********

In this chapter, we quickly setup the basic Patcher configuration for hacking on XEmacs. Adapt the example as you wish. Let's make some assumptions first:

  * You own a computer.

  * You have the add-log library from the xemacs-base package, version 1.48 or later, installed on your system.

  * You're using XEmacs from the CVS repository.

  * Your local copy of the repository is located in /usr/local/src/XEmacs-21.5.

  * Your local copy of the repository is up-to-date, but you've done some hacking in the sources that you'd like to submit.

  * Since you're lazy, you didn't write the ChangeLog entries yet.

Setting up Patcher
==================

The first thing to do is to make patcher aware of your ``XEmacs'' project. Put this in your .emacs file:

     (setq patcher-projects
           '(("XEmacs" "/usr/local/src/XEmacs-21.5"
              :to-address "xemacs-patches@xemacs.org")
             ))

As you can imagine, patcher-projects is a user option in which you store information about the projects you want to manage with Patcher. It is actually a list of what's called project descriptors. Here's the meaning of the only project descriptor we have in the example above: we have a project named ``XEmacs'', located in /usr/local/src/XEmacs-21.5 and for which emails should be sent to xemacs-patches@xemacs.org.

Note the particular syntax for specifying the mailing address. This is what's called a project option. Contrary to the project's name and directory, which are mandatory and always appear as the first and second elements of a project descriptor, project options are optional and can appear in any order.

Calling Patcher
===============

Now you want to build a patch with your changes, and prepare a message to submit them. The way Patcher works is currently to setup the message first, and then to control all subsequent operations from there. In other words, to create a patch, you actually ask Patcher to prepare a mail. Type this:

     M-x patcher-mail

First, you're prompted (with completion) for a project name (the first element of each project descriptor, remember ?). We currently only have an ``XEmacs'' project, so hitting TAB will directly fill the minibuffer in with this only choice. Then, you're prompted for a subject line that will be used in the mail. Say something sensible.

Three operations are now executed in turn:

 1. Patcher prepares a mail buffer. The message will be sent to the address you specified with the :to-address project option, and the subject line now reads ``[PATCH] something sensible''.

 2. Patcher now builds the patch. The command used to do this is cvs -q diff -u (this is also a project option). Upon successful completion of this command (we assume that's indeed the case), the patch is inserted into the mail buffer. Some information about the patch is provided just above it (the command used, the files affected and so on).

 3. Finally, Patcher generates ChangeLog skeletons from what it understands of the patch. This involves visiting the appropriate ChangeLog files, and creating initial entries.

Filling the ChangeLogs
======================

Patcher has just created initial ChangeLog entries for you. You must now browse through the ChangeLog file(s) and fill the entries as you see fit. Once you're done, you can very well save the ChangeLog buffers. However, don't kill them ! Don't even think about it. Patcher still needs them. Now, please return to the mail buffer.

Filling the message
===================

Now that you're satisfied with your ChangeLog entries and you've returned to the mail buffer, you want to write some explanation text in the message. I'll let you do that. You also want to insert the ChangeLog entries corresponding to your patch, since they are usually much more readable than the patch itself.

Inserting your ChangeLog entries in the mail buffer is as simple as typing C-c C-p i. This actually calls the function patcher-insert-change-logs, which places them just above the patch, with a short information line (per ChangeLog file) on top.

Committing the Patch
====================

If you have commit access to your project, you should read this. Otherwise, you may directly see Sending the Message.

Committing your changes involves three steps: preparing the commit command, preparing the commit log message, and actually committing the changes. Although Patcher can do all of this in one shot, it lets you control each step by default.

In order to start the commit process, simply type C-c C-p c. This calls the function patcher-commit-change. Congratulations. You've just been transported to a new buffer, the *Patcher Log Message* buffer. This buffer lets you edit the log message that will accompany your commit. Note that the message is initialized with the subject line of your mail. This is also a project option.

Once you're satisfied with the log message, type C-c C-c. This calls the function patcher-logmsg-commit, which computes the commit command to use. The command is displayed in a special buffer, the *Patcher Commit Command* buffer. The default commit command is cvs commit, which of course is also a project option. Note that Patcher stores the log message in a temporary file and uses the -F cvs commit option. Finally, note that Patcher has automatically appended the affected ChangeLog files to the commit command.

At this point, you have the opportunity to abort the commit operation. Otherwise, answer positively and the commit will be executed. If you had not previously saved the ChangeLog files, Patcher will do it for you just before committing.

Sending the Message
===================

Sending the message has actually nothing to do with Patcher. It depends on the method you use for sending mails, but will usually be done via a C-c C-c command of some sort. On thing to note however: if you've committed your changes via Patcher, the message has been slightly modified: the subject line now reads ``[COMMIT] something sensible'' instead of ``[PATCH] ...'', and a short commit notice has been inserted just at the beginning of the message's body.

That's it. That was easy. Congratulations on your first shot at Patcher, anyway ! Of course, Patcher is much more powerful and customizable than what has been described in this chapter. For a complete documentation on how to use and customize Patcher, please refer to User Manual.

User Manual
***********

This chapter provides a step-by-step guide to using Patcher. Everything there is to know about Patcher is here, though the features are introduced progressively.

All user options that are going to be presented in this manual can be found in the patcher customization group, or a subgroup of it.

Project Descriptors
===================

Projects specifications are stored in patcher-projects. This user option is actually a list of project descriptors. Each project descriptor has the following form: (NAME DIR :OPTION VALUE ...)

NAME is a string naming your project, DIR is a string specifying the directory in which it resides. The remainder of a project descriptor is a sequence of zero or more option/value pairs, that we call project options. All option names start with a colon. The type of a value depends on the corresponding option. For example, there is a project option named :to-address, whose value should be a string giving the email address to which you want to send Patcher messages.

When Patcher needs the value for a particular project option, it looks for it directly in the project descriptor, but also in other places. This process is described below.

Themes
------

If you have several projects sharing the same option set, you might want to setup a theme. Themes are named collections of project options.

Themes are stored in the patcher-themes user option. This option is a list of themes. Each theme has the following form: (NAME :OPTION VALUE ...).

NAME is the theme's name (a symbol). The remainder of the list is a sequence of zero or more option/value pairs, just like in project descriptors.

In order to use a theme in a given project, a :themes project option is provided. It is a list of theme names (symbols). Use this option in your project descriptor, and the project will implicitly inherit all options from the corresponding theme.

One important note: as :themes is a project option, it can appear in a theme. In other words, themes can inherit from other themes. When Patcher tries to retrieve an option, the themes tree is traversed in depth first.

Because themes can contain themes, a bogus setting might lead to an infinite loop (a cycle in a theme graph). To prevent this, the patcher-max-theme-depth user option is provided. It represents the expected maximum theme nesting level, and defaults to 8.

Patcher comes with a set of built-in themes for several revision control systems. These are Git, Mercurial (Hg), Darcs, Subversion (Svn) and CVS and PRCS. Look at the value of patcher-built-in-themes to see what's in them. Each of these themes have a -ws counterpart which eliminates white-space differences in diff outputs. This comes in handy if you perform some kind of automatic white-space cleanup in the files you edit, especially when you let Patcher generate the ChangeLog entries.

While you can't modify the value of patcher-built-in-themes, you're free to do whatever you want in patcher-themes, including creating a theme with the same name as a built-in one. This new theme will take precedence over the other. Having this built-in variable (a constant, actually) lets me modify its value from release to release without risking to smash your own adjustments.

Project inheritance
-------------------

When two projects are very similar, you might want to use the project inheritance mechanism described below.

There is a special project option called :inheritance. This option must be a list of project names (strings). The inheritance of a project defines a list of projects from which to inherit options.

One important note: inherited projects might have their own :inheritance option set to other projects in turn. In other words, the project inheritance can be more than one level deep. When Patcher tries to retrieve an option, the inheritance tree is traversed in depth first.

Because inherited projects can inherit from projects, a bogus setting might lead to an infinite loop (a cycle in a project graph). To prevent this, the patcher-max-inheritance-depth user option is provided. It represents the expected maximum project inheritance level, and defaults to 8.

The :inheritance project option is somewhat special in the sense that it can't appear in a theme. We will encounter other exceptions later in this manual.

Fallbacks
---------

For each existing project option, Patcher also has a fallback user option with a default value that would be shared among all (or some of) your projects. The name of the fallback is obtained by replacing the colon in the project option's name with the prefix patcher-default-. For example, the fallback corresponding to the :to-address project option is named patcher-default-to-address.

The :inheritance project option is also special in the sense that it doesn't have a corresponding fallback. We will encounter other exceptions later in this manual.

In the remainder of this manual, we will rarely mention the fallbacks again. When we introduce a new project option, just remember that it always has a corresponding fallback (well, not always, as you just discovered).

Retrieval
---------

When Patcher needs the value of a particular project option, it looks for it in the following manner:

  * First, it looks directly in the project descriptor to see if the option is given.

  * If that fails, it next tries the given themes, if any. This involves recursively traversing the project's themes tree. Options successfully retrieved in themes are said to be themed.

  * If that still fails, it then tries the inherited projects, if any. This involves recursively traversing the project's inheritance tree. Options successfully retrieved in inherited projects are said to be inherited. Note that in turn, such options could have been actually themed in the inherited project.

  * If that fails again, it finally falls back to the value given in the corresponding fallback (if it exists). In such a case, the option is said to be fallbacked.

Note that a value of nil for a project option is an actual value. It is not equivalent to an option being unset. As a consequence, if Patcher finds a project option with a value of nil somewhere, it will use it and stop the search, even if a non nil value could be retrieved later from a theme, an inherited project or a fallback. This provides you with a way to annihilate themed, inherited or fallbacked options.

Inheritance or theme ?
----------------------

At that point, you might be wondering why the themes and inheritance concepts were both designed, since they actually perform very similar tasks. Good question. Here is a good answer.

Projects might share options for different reasons. For example, my ``XEmacs'' (source) and ``XEmacs Packages'' projects share many options (To: address, From: address, diff and commit commands and so on) because they both relate to XEmacs. On the other hand I have personal but totally unrelated projects that share the same commands because they are all handled through a common system: Darcs.

In other words, you should rather use the inheritance mechanism when projects relate to each other, and the theme mechanism for settings that are orthogonal the projects they apply to.

Mail Preparation
================

Patcher currently uses the mail buffers as ``master'' buffers for controlling all operations: building a patch, creating the ChangeLog entries, committing... all is done from the mail buffer. Note however that you don't need to actually send mails to use Patcher (see Fake Mail Method).

To use Patcher on a certain project, you start by preparing a (possibly fake) mail. There are several ways to do so: you could start a brand new message, ``adapt'' a message already in preparation to Patcher, or even compose some sort of a Patcher reply to another message.

 -- Function: patcher-mail
     Start composing a brand new Patcher message. This function interactively prompts you for the name of the project and for a (mail) subject line.

 -- Function: patcher-mail-adapt
     Assuming that you are already editing a message (with your usual MUA), this function ``adapts'' it to Patcher by prompting you for the name of a project. Note that this function does not prompt you for a subject.

If you're using Gnus to read mail and have properly insinuated it (see Insinuation), Patcher offers different Gnus-like ways to answer mails and adapt them to Patcher. All the functions below are available from both the Gnus Summary and the Article buffer.

 -- Function: patcher-gnus-summary-followup
     Compose a followup to the article, and adapt it to Patcher. This function is bound to C-c C-p f.

 -- Function: patcher-gnus-summary-followup-with-original
     Idem, but also cite the original article. This function is bound to C-c C-p F.

 -- Function: patcher-gnus-summary-reply
     Like patcher-gnus-summary-followup, but compose a reply. This function is bound to C-c C-p r.

 -- Function: patcher-gnus-summary-reply-with-original
     Idem, but also cite the original article. This function is bound to C-c C-p R.

In any case, Patcher starts working on the project (by first creating the patch) after the message is prepared. Because of this, we'll start by reviewing the mail-related customizations you might want to setup.

Mail Methods
------------

Since there are different mail packages working in XEmacs, Patcher supports different methods for preparing messages. You can specify the method you prefer in the :mail-method project option. The value must be a symbol.

Standard Mail Methods
.....................

Patcher currently supports sendmail, message and Gnus natively and through the compose-mail interface. Other MUA might be partly supported when used with compose-mail. Patcher will probably suffer from non critical deficiencies in that case however (it will issue warnings).

compose-mail
     This is the default. It is implemented via the function patcher-mail-compose-mail which calls compose-mail to prepare the message. If you are not familiar with compose-mail, you might also want to throw an eye to the user option mail-user-agent. If your project does not specify an address to send the message to (see Message Customization), it is prompted for.

sendmail
     A direct interface to the mail function from the sendmail package. It is implemented via the function patcher-mail-sendmail. If your project does not specify an address to send the message to (see Message Customization), it is prompted for.

message
     A direct interface to the message-mail function from the message library (it is part of Gnus). It is implemented via the function patcher-mail-message. If your project does not specify an address to send the message to (see Message Customization), it is prompted for.

gnus
     A direct interface to the gnus-post-news function from the Gnus package (it can also send mails...). It is implemented via the function patcher-mail-gnus. This mail method is interesting when you maintain a special mail group for messages that you send with Patcher, most probably because they are sent to some mailing-list, such as xemacs-patches@xemacs.org.

     This method uses a Gnus group name and acts as if you had type C-u a on that group in the *Group* buffer, hence honoring the group parameters and posting-styles. If your project does not specify a Gnus group name (see Message Customization), it is prompted for.

This last mail method is special in the sense that it requires a running Gnus session to work. If that's needed, Patcher can start Gnus for you in several ways, according to the following user options:

patcher-mail-run-gnus
     If nil, Patcher will never start Gnus and abort the operation instead. If t, Patcher will always start Gnus when needed. If 'prompt, Patcher will ask you what (you want) to do. This is the default behavior.

patcher-mail-run-gnus-other-frame
     Used when Patcher has to start Gnus by itself. If nil, continue using the current frame. If t, start Gnus in another frame (this is the default). If 'follow, start Gnus in another frame, and use this new frame to prepare the Patcher mail.

Fake Mail Method
................

At that point, you might be wondering why the mail method is a project option and not simply a user option, since you probably only use one mail agent at all. Right. But you might one day work on projects for which you don't need to send messages at all. This could happen if you start using Patcher on a project of your own for instance. For that reason, there is a fake mail method available. It is implemented via the patcher-mail-fake function and calls no particular mail user agent. Once you type C-c C-c to virtually send the fake message, it only performs some cleanup.

All right. But did we really need this fake method ? I mean, one could use the usual mail method, and simply not send the message in the end. Huh, yeah, ok... Actually, it is very probable that in a future release of Patcher, the mail buffer won't be the master buffer anymore, and mail sending will be just another optional step in the process. In that case, the mail method is likely to move away from project option to standard user option.

Other Mail Methods
..................

If you're not satisfied with the provided mail methods (want a vm one ?), you can provide your own, more or less. Here's what to do: set your :mail-method project option to, say, foo, and write your own function which must be named patcher-mail-foo.

This function must take two arguments (a project descriptor and a string containing the subject of the message), and prepare a mail buffer. If you want to do this, you should see how it's done for the built-in methods.

Note that the mail adaptation facility won't be available for your custom method. For that, I would have to hack the internals of Patcher.

Message Customization
---------------------

When preparing a message, Patcher can fill some parts of it for you. Here's a list of mail-related project options.

:user-name
     The name (your name) to use when composing the message. It will affect the From: header. This option is used by all mail methods but fake. If not given, user-full-name is used.

:user-mail
     The mail (your mail) address to use when composing the message. It will affect the From: header. This option is used by all mail methods but fake. If not given, user-mail-address is used.

:to-address
     The address to send messages to (a string). This option is used by all mail methods but gnus and fake. If not given, it is prompted for when calling patcher-mail.

:gnus-group
     The Gnus group name to use for posting messages (a string). This option is used only by the gnus mail method. If not given, it is prompted for when calling patcher-mail.

     Note that if you configured your name and mail in Gnus, for instance through posting styles, these configurations take precedence over the corresponding Patcher options.

:subject-prefix
     A prefix for the subject line of messages. It can be nil or a string. By default, ``[PATCH]'' is used. This part of subjects is never prompted for. A %n occurring in this string will be replaced with the project name. Also, a space is inserted between the prefix and the remainder of the subject, when appropriate.

:subject
     A default value for prompted subjects (a string). A %n occurring in this string will be replaced with the project's name (see Subproject Naming). Please note that this is used only to provide a default value for prompted subjects. Subjects are always prompted for.

:mail-prologue
     A prologue to insert just at the top of a message body (a string).

Patch Generation
================

Patcher creates patches by diffing your local copy of the project against the repository. This is done automatically after preparing a message, so you shouldn't normally bother to do it manually. That situation might still happen from time to time, like, if you further modify the sources, or if the initial operation failed for some reason (see More On Commands).

The way to (re)generate the patch manually is to call patcher-generate-diff from the mail buffer. This function is bound to C-c C-p d in this buffer. You can both customize the diff command used to (re)generate the patch, and restrict the diff to a subset of the project's files.

When possible, Patcher also tries to check that your project is up-to-date with respect to the archive, and will inform you otherwise.

By the way, (re)generating the patch does not necessarily mean that it is directly inserted into the mail buffer. This also depends on the ChangeLogs behavior (see ChangeLogs Handling).

Diff Command
------------

The diff command used to generate the patch is specified by the :diff-command project option. You can also punctually change this command by calling patcher-mail or patcher-generate-diff with a prefix argument. Patcher will then prompt you for a new command and use it exclusively for this particular patch.

For detail about the format of this option, see Patch Restriction. See also More On Commands.

Diff Headers
------------

When Patcher generates a diff, it needs to associate every hunk with the corresponding source file (and possibly with the corresponding ChangeLog file as well). Unfortunately, different revision control systems might generate different diff outputs, making this association difficult to establish.

Patcher provides a :diff-header project option to help. Its value is of the form (REGEXP NUMBER1 NUMBER2). REGEXP is used to match the beginning of a diff output while NUMBER1 and NUMBER2 are the parenthesized levels in which to find the corresponding old and new file names.

When the change involves modifying a file's contents, the old and new file names will be the same. However, they can be different in several situations, like when a file is renamed, created or deleted. In case of creation or deletion, some revision control systems use ``/dev/null'' to denote a virtual old or new file.

If you want to see some examples, have a look at the built-in themes in patcher-built-in-themes (see Themes). They contain presets for different revision control systems, along with suitable :diff-header options.

Also, you should pay attention to the fact that the values of the :diff-header and :diff-command options may depend on one another to work properly. For instance, the diff output of Mercurial looks different when you use the --git option.

Diff Line Filter
----------------

When generating a global diff, that is, without specifying the files affected by the patch explicitly (see Patch Restriction), some uninformative lines might be present in the output. A typical example is files present in your local copy but unknown to the CVS server. Such files are indicated by a question mark in diff outputs.

Patcher has a project option named :diff-line-filter that lets filter out such unwanted lines when inserting the diff in the mail buffer. This must be a regular expression matching a whole line. Caution however: do not put beginning or end of lines markers in your regexp. Patcher will do it for you.

By default, the value is "\\? .*", which excludes files unknown to the CVS server.

Patch Restriction
-----------------

Sometimes, you don't want to generate a global patch, but instead work on a subset of the project's files. Patcher understands this concept as working on a subproject.

As for working on whole projects, there are several alternatives to start working on a subproject:

 -- Function: patcher-mail-subproject
     This function behaves exactly like patcher-mail, except that it also prompts you for the files affected by the patch. You can specify files as well as directories, use wildcards, just as you would construct a command line diff.

 -- Function: patcher-mail-adapt-subproject
     Idem, with respect to patcher-mail-adapt.

Finally, all the Gnus-specific reply functions (see Mail Preparation) take an optional prefix argument that make them work on subprojects.

Two important things are to be kept in mind when working on subprojects:

  * It is not necessary (it is even forbidden) to specify the ChangeLog files. Patcher will automatically find them for you. In other words, only specify source files, not ChangeLog files.

  * Don't mistake the prefix argument of patcher-mail, patcher-mail-subproject and patcher-generate-diff as a way to specify files. It is not meant for that. It is meant only to temporarily modify the diff command itself, not the files to which it applies.

When working on a subproject, Patcher uses the same diff command as the one used for the whole project, that is, the value of the :diff-command project option. In the case of a subproject however, Patcher has to know where to put the files on the command line (even if it's usually the last part of it). This is done with the special construct %f: a %f appearing in the diff command will be replaced with the specified files (and the computed ChangeLog files) for a subproject, and will simply be removed when working on the whole project.

For example, the built-in CVS theme (see Themes) has the :diff-command option set to cvs -q diff -u %f.

There is another special construct available in this command: a %n will be replaced with the project's name (see Subproject Naming). This may be useful in commands with weird options syntax, like PRCS.

For a more advanced way of handling subprojects, see More On Subprojects.

Patcher Instances
-----------------

The concept of subprojects brings up the question of having Patcher working on different patches at the same time. It is possible under some conditions:

  * You can have as many simultaneous Patcher instances as you want on different projects (you would not define two projects sharing the same directory, would you ?).

  * You can have as many simultaneous Patcher instances as you want on the same project, as long as there is no overlapping between each subproject. This means that you can't have source files, or even ChangeLog files in common.

This last point will be subject to improvements in the future.

Diff Prologue
-------------

Patcher can (and does) insert a special prologue just above a patch in the message in preparation. This prologue gives information such as the diff command used, the files affected and so on.

The function used to generate this prologue can be specified with the :diff-prologue-function project option. A value of nil means don't insert any prologue. By default, the internal function patcher-default-diff-prologue is used. If you want to provide your own, here how to do it.

Your function should take one argument indicating the kind of diff (a symbol), and perform insertion at current point in the current buffer. The possible values for the argument are:

sources
     indicates a source diff only,

change-logs
     indicates a ChangeLog diff only,

mixed
     indicates a diff on both source and ChangeLog files.

The following variables are bound (when appropriate) when this function is executed:

name
     the name of the current Patcher project,

source-diff
     the command used to create a source diff,

change-log-diff
     the command used to create a ChangeLog diff,

source-files
     sources files affected by the current patch,

change-log-files
     ChangeLog files affected by the current patch.

In the case of a mixed diff, a nil value for change-log-diff indicates that the same command was used for both the source and ChangeLog files.

ChangeLogs Handling
===================

ChangeLogs management in Patcher involves two aspects: how ChangeLog entries are created, and how they appear in the messages. Both aspects can be customized beyond your craziest dreams.

ChangeLogs Updating
-------------------

The way Patcher deals with ChangeLogs is controlled via the :change-logs-updating project option. Its value (a symbol) must be one of automatic (the default), manual or none.

Automatic ChangeLogs
....................

Automatic ChangeLogs mode is the default. Each time you (re)generate a diff, Patcher (re)creates ChangeLog skeletons in the appropriate ChangeLog files, by analyzing the generated diff. You then need to fill the entries manually.

ChangeLog skeletons are not generated by Patcher directly, but rather by the function patch-to-change-log of the add-log library from the xemacs-base package. This function supports only standard and CVS diff, in unified format. For revision control systems that output something different, Patcher provides a :diff-cleaner option. This option names a function that will be used to ``cleanup'' the diff (so that it looks like a standard one, just before calling patch-to-change-log. Patcher also comes with a generic cleaner function named patcher-generic-diff-cleaner which is used by default and works correctly with Git, Mercurial, Darcs and PRCS, as long as you use the corresponding built-in themes (see Themes), or in fact, as long as the corresponding :diff-header option is correct (see Diff Headers).

In order to build the ChangeLog skeletons, the source files must be visited. Patcher has a :kill-source-files-after-diffing project option that lets you decide whether you want to kill the source buffers just after diffing or not. The value can be either nil or t. By default, the behavior is to preserve the source files, since you might need them for reference when filling the ChangeLog entries. If you don't use automatic ChangeLogs mode, it makes sense to set this option to t.

Patcher has two project options that give you some control on the generated ChangeLog skeleton: :change-logs-user-name and :change-logs-user-mail. As you might expect, these are strings defining your name and mail address for ChangeLog entries'headers. When nil, Patcher falls back to (respectively) the :user-name and :user-mail project options. If in turn set to nil, Patcher lets the function patch-to-change-log decide what to use (most probably what the user options user-full-name and user-mail-address say).

Normally, you don't modify source files when working with Patcher. However, ChangeLog files need update and saving in automatic mode. Patcher provides two hooks for plugging in additional processing on ChangeLog files.

  * :notice-change-log-hook This hook is run every time Patcher ``notices'' a ChangeLog file. Noticing a ChangeLog file in this context means figuring out that it is involved in the current patch. Every function in this hook will be given the ChangeLog file name (relative to the project's directory) as argument.

  * :after-save-change-log-hook This hook is run every right after you save a ChangeLog file. The functions in this hook are executed in the ChangeLog's buffer.

Manual ChangeLogs
.................

In manual mode, Patcher assumes that you create ChangeLog entries manually, as you write the code, so it won't create ChangeLog skeletons. It is important to understand that in this situation, ChangeLog entries must have been written before you call Patcher. Patcher won't let you write them in the process.

Even in manual mode, Patcher might still need to know the affected ChangeLog files (for the commit process) and your exact ChangeLog entries in each of these files (for insertion in the message). The ChangeLog files are automatically deduced from the patch. When that's required, however, you will be presented with each ChangeLog file in turn, and invited to precise the number of ChangeLog entries concerning this patch. These entries must of course appear at the top of the file.

No ChangeLogs
.............

This mode is for projects that don't do ChangeLogs. Patcher won't try to create ChangeLog entries, and won't expect that you have written ChangeLog entries either.

Note that if you do have ChangeLog files in this mode, they will be regarded just as normal ones. As a consequence, this is a case where it is not forbidden to list them explicitly as part of a subproject (see Patch Restriction), although I don't see why you would want to do that.

ChangeLogs Appearance
---------------------

When Patcher has to deal with ChangeLog files, you insert ChangeLog entries in the message buffer by calling the function patcher-insert-change-logs. It is bound to C-c C-p i in the mail buffer. Note that if ChangeLogs are written in advance, you don't have to do that, as Patcher will do it automatically. You have to call this function by hand only in automatic updating mode (see ChangeLogs Updating).

In all circumstances however, you can use this function to reinsert the ChangeLog entries into the mail buffer. That might come in handy if you further modified them after the initial insertion (it's never too late to fix a typo).

The appearance of ChangeLog entries in the message is controlled by the :change-logs-appearance project option. Its value must be a symbol from the following:

verbatim
     This is the default. ChangeLog entries appear just as text in the message, above the patch. Most people prefer this kind of appearance since it is the most readable.

packed
     ChangeLog entries appear as a patch (they are diff'ed against the archive). This patch is however distinct from the source patch, and appears above it.

patch
     ChangeLog entries appear as a patch (they are diff'ed against the archive), and this patch is integrated into the source patch. In other words, the message looks like a global patch integrating both the sources and the ChangeLogs.

When the ChangeLogs appearance is either packed or patch, the diff command used to generate the patch is controlled by the :change-logs-diff-command project option. The value can be the symbol diff, meaning that the same diff command is to be used as for the sources (see Diff Command), or it can be a string specifying an alternate command.

When diffing ChangeLog files, it is strongly recommended that you remove contexts from the diff, because otherwise, ChangeLog patches often fail to apply correctly.

As in the case of the :diff-command project option (see Patch Restriction), a %f serves to indicate where to put the ChangeLog files on the diff command line, and a %n is replaced with the project's name (see Subproject Naming). See also More On Commands.

Given these two remarks, you should now understand why the default value for patcher-default-change-logs-diff-command is cvs -q diff -U 0 %f.

ChangeLogs Prologue
-------------------

ChangeLog prologues are small pieces of informative text that Patcher adds above each ChangeLog insertion in the mail buffer.

When the ChangeLogs appearance is verbatim, Patcher inserts one prologue per ChangeLog file. The prologue's contents is controlled by the :change-logs-prologue project option (a string). A %f appearing in this string will be replaced with the ChangeLog filename. The default value for patcher-default-change-logs-prologue is "%f addition:".

When the ChangeLogs appearance is packed, Patcher inserts only one prologue for the whole ChangeLogs patch. When patch, there is a single prologue for both the ChangeLogs and the sources. For customizing the prologue in both of these cases, see Diff Prologue.

Project Check In
================

If you have the privilege to commit your changes yourself, you might do so directly from the mail buffer, as the last operation before actually sending the message. This is done by calling the function patcher-commit-change which is bound to C-c C-p c in the mail buffer.

Committing directly from Patcher has the advantage that both the commit command line and the commit log message (see Log Message Handling) are constructed automatically. Of course, you still have an in-depth control on the commit process.

Commit Command
--------------

The command used to to commit a patch is specified by the :commit-command project option (a string). You can also temporarily change the command in question by calling patcher-commit-change with a prefix argument. As usual, note that this prefix argument is not meant to modify the affected files on the command line. It's meant only to punctually modify the commit command itself. The affected files are computed automatically by Patcher.

The commit command accepts (and maybe requires) special constructs:

  * A %n occurring in the string will be replaced with the project's name (see Subproject Naming).

  * A %f occurring in the string will be replaced with the files affected by the patch (ChangeLogs included, this time), or discarded if the patch is global.

  * A %?f{blabla} occurring in the string will be replaced with ``blabla'' if %f would expand to something, or discarded otherwise (this is an ``if %f'' form).

  * A %!f{blabla} occurring in the string will be replaced with ``blabla'' if %f would expand to nothing, or discarded otherwise (this is an ``if not %f'' form).

  * A %s occurring in the string will be replaced with the name of a file containing the commit log message (see Log Message Handling). This file is a temporary file handled by Patcher.

  * A %S occurring in the string will be replaced with the commit log message itself (see Log Message Handling). Since the intent here is to use the message as a command-line argument, it is quoted against shell expansion.

Please note that a %f is required in your commit commands, unless you know for sure that you will never ever work on a subproject (see Patch Restriction). But you never know that. Besides, you should always also provide either a %s or a %S, unless your archival software does not support log messages.

Given that, you should now understand why the default value for patcher-default-commit-command is cvs commit -F %s %f.

Log Message Handling
--------------------

Most project management tools understand the concept of a log message: a short yet informative message that accompany the commit operation, which is also stored in the repository.

Before a commit operation, Patcher always builds an initial log message, based on certain elements under your control (see Log Message Elements). Afterwards, you can decide on whether you want some further (manual) edition of log message, or whether you want to commit immediately.

The :edit-log-message project option lets you specify this behavior. If t (the default), you will be able to manually edit the log message. If nil, Patcher will proceed directly to the commit operation.

Please note that Patcher stores log messages in temporary files that will be used later by the commit command.

Log Message Elements
....................

Patcher has the ability to initialize the log message with different elements. These elements are specified with the :log-message-items project option. Its value is either nil, meaning that you don't want any initialization, or a list of symbols specifying the elements you desire. The available items are:

subject
     The subject of the message. The subject's prefix is automatically removed.

compressed-change-logs
     The ``compressed'' ChangeLog entries. Only the most important part of the ChangeLogs is preserved, so the entries appear in a more compact fashion.

change-logs
     The raw ChangeLog entries.

By default, only the message's subject is used. When using more than one item, they appear in the order specified above. If anything appears before the raw ChangeLog entries, a separator string is used. This string is specified by the :change-logs-separator project option. By default the string looks like ``--- ChangeLog entries follow: ---''.

Log Message Editing
...................

If so required, Patcher lets you manually edit the log message after having initialized it. Log message edition happens in a special buffer, the *Patcher Log Message* buffer.

While editing this buffer, commands to insert the items described in Log Message Elements are at your disposal. These commands perform insertion at point:

patcher-logmsg-insert-subject
     Bound to C-c C-p s. Insert the message's subject (sans the prefix).

patcher-logmsg-insert-compressed-change-logs
     Bound to C-c C-p c. Insert the compressed ChangeLog entries.

patcher-logmsg-insert-change-logs
     Bound to C-c C-p l. Insert the raw ChangeLog entries. Use a prefix argument if you also want the ChangeLogs separator string to be inserted.

In addition to these commands, you can also completely reinitialize the log message according to the specified items, by calling the function patcher-logmsg-init-message, bound to C-c C-p i. Caution: this command first erases the buffer.

Finally, once you're happy with your log message, you proceed to the commit operation by calling the function patcher-logmsg-commit, bound to C-c C-c.

Commit Operation
----------------

The commit operation occurs after typing C-c C-p c from the mail buffer, if you have not required log message edition, or after typing C-c C-c from the *Patcher Log Message* buffer otherwise.

At that point, Patcher has constructed a proper commit command. You still have an option to abort the process, though: the :confirm-commits project option lets you specify whether to require confirmation before committing. If t (the default), Patcher will display the constructed commit command and ask for a confirmation before proceeding. If nil, Patcher will commit immediately.

After the commit operation, Patcher changes some parts of the mail buffer in the following manner:

  * The subject prefix is changed to that specified by the :subject-committed-prefix project option (a string), unless it is nil. By default, ``[COMMIT]'' is used.

  * A commit notice is added right at the beginning of the message's body. This notice is specified by the :committed-notice project option. It can be nil or a string. By default, it reads ``NOTE: this patch has been committed.''.

Mail Sending
============

Sending the message will most probably be done by typing C-c C-c in the mail buffer. This is also the case when you're using the fake mail method, by the way.

Before Sending
--------------

There are circumstances in which Patcher will perform some checkings on your message when you send it, just before it is actually sent:

  * ChangeLogs insertion

     In case of manual ChangeLog insertion (see ChangeLogs Appearance), Patcher can check that you have indeed inserted the ChangeLog entries before sending the message. This behavior is controlled by the patcher-mail-check-change-logs-insertion user option. A value of nil means never check (the message will be sent as-is). A value of t means check, and abort the sending if the ChangeLog entries are missing. A value of ask (the default) means ask for your opinion on this terrible matter.

  * Commit Operation

     Patcher has a :commit-privilege project option; a boolean specifying whether you're likely to commit your changes by yourself.

     In case of commit privilege, Patcher can check that you have indeed committed your changes before sending the message. This behavior is controlled by the patcher-mail-check-commit-action user option. A value of nil means never check (the message will be sent as-is). A value of t means check, and abort the sending if the commit operation has not been performed. A value of ask (the default) means ask for your opinion on this rather unfortunate situation.

Two notes on these checkings:

  * For uninteresting technical reasons, Patcher does not currently (and will probably never) offer you an automatic ChangeLogs insertion or commit operation, at mail sending time, but just abort the sending process in some circumstances. That's not a big deal though.

  * For other uninteresting technical reasons, these checkings require a native knowledge of your mail user agent. Patcher does not currently support all mail user agents on earth (I'll add them on demand however). If that's the case, you will be warned and invited to send me a message. Also, you can send me one on April 21st: it's my birthday.

After Sending
-------------

After sending the message, Patcher also performs some cleanup operations, that you can customize. The cleanup is controlled by the following project options. Each one is a boolean option which defaults to t.

:kill-source-files-after-sending
     Whether to kill source files after sending the message. If nil, the source files will remain visited.

:kill-change-logs-after-sending
     Whether to kill ChangeLog files after sending the message. If nil, the ChangeLog files will remain visited.

More On Commands
================

This section deals with information that apply to all commands used by Patcher (diff and commit operations).

Prefixing Commands
------------------

If you're working on a distant archive and you're behind a firewall, you might need to prefix all your commands with something like runsocks. Of course, this can be done manually in all your command settings, but Patcher offers you a simpler way to do it.

There is a project option named :pre-command which can be used for this kind of thing. It must be a string that will be prepended to all operations performed by Patcher.

Error Handling
--------------

From time to time, commands may fail for different reasons. Patcher tracks the failures in these commands and lets you know when that happens. The :failed-command-regexp project option lets you specify a regular expression to match with the output of an aborted command. By default, the value is "^cvs \\[[^]]* aborted\\]".

More On Subprojects
===================

We've already seen how to work punctually on a subproject, that is, on a subset of a project's files (see Patch Restriction). If you happen to work more than once on the same project subset, it will quickly become annoying to have to specify explicitly the same files over and over again. Patcher offers you a way to permanently define subprojects.

Defining Subprojects
--------------------

The user option patcher-subprojects stores a list of subproject descriptors. A subproject descriptor is almost the same as a project descriptor, with a few exceptions:

  * Instead of the project directory field (the second field in a project descriptor), you rather specify the name of the project this subproject is based on.

  * In addition to the standard project options we've already seen, two subproject options are available:

     :subdirectory
          This lets you specify a subdirectory of the original project's directory in which the whole subproject resides.

     :files
          This lets you specify a list of files or directories composing the subproject. Each file specification can contain wildcards. If a :subdirectory subproject option is given, these files or directories should be relative to this subdirectory. Otherwise, they should be relative to the parent project's directory.

     Please note that these subproject options have no corresponding fallback (that would be meaningless). They can't appear in a theme either.

  * Subprojects don't have an :inheritance mechanism. Instead, they implicitly inherit from their base project (which in turn can inherit from other projects).

Here are some important remarks about subprojects:

  * A subproject with neither a :subdirectory nor a :files option is exactly the same as the base project, apart from project options that you would override.

  * Since permanent subprojects are defined statically, they should be used with the normal Patcher functions like patcher-mail. You don't need to use the *-subproject versions any more.

  * Because of that, projects and subprojects can't have names in common. If that happens to be the case, Patcher will blindly use a subproject rather than a project of that name

  * So what happens if you persist in using a *-subproject function on a permanent subproject ? Well, you punctually work on a subsubproject...

Subproject Naming
-----------------

As you already know, Patcher distinguishes projects by their NAME field in the patcher-projects and patcher-subprojects user options. This is problematic, however, if you define different patcher projects for a single physical project, and the commands require the project's name. That might for instance be the case with PRCS (decidedly) weird options syntax.

To remedy this problem, patcher provides a :name project option. If set, it will actually be used for all %n substitutions where the project's name (in the Patcher sense) would normally be used.

If you want to use the project's name in the Patcher sense, regardless of the value of the :name option, use %N instead of %n.

Command Directory
-----------------

Some revision control systems, like CVS, work on a per-file basis. Some others, like PRCS, work only globally. This has an important implication for subprojects being sudirectories of other projects. Indeed, while CVS, for instance, can be executed anywhere, PRCS can only be run in the base project's root directory.

If you want to define projects for which the revision control system can be executed in only one directory, Patcher provides you with the :command-directory project option (a string). This directory can be specified relative to the project's directory (but note that it must go upwards).

All commands (diff and commit ones) will be executed from there. Also, note that the command directory does not change the way you might specify files. Patcher modifies all needed paths automatically to handle the command directory properly.

XEmacs Development
******************

Here is some specific information on how to setup Patcher for XEmacs developers. This assumes you're a committer to the mercurial repository of the 21.5 branch.

The way I do it, I have a directory named /usr/local/src/xemacs-21.5 which is a clone of the Debian Mercurial repository. Let's call it the local trunk. I have set the proper default and default-push options in /usr/local/src/xemacs-21.5/.hg/hgrc so that I can push, pull, fetch or whatever without any argument on the command line. I also have set the username option to my XEmacs identity (that's mainly for the commit log messages).

When I work on a new feature, I do it in a directory named /usr/local/src/xemacs-21.5-new-feature, in which I commit regularly and occasionally merge with the main repository to keep up to date. When I'm satisfied with the feature, it's time to integrate it, but I don't want to import my whole personal history; so I just apply the final diff to my local trunk (which must be up to date), commit locally with Patcher and then push it up by hand.

Under those conditions, the Patcher setup is quite simple:

  * Set the commit-privilege option to t.

  * Use the mercurial or mercurial-ws built-in theme.

  * Use the fake mail method, because messages are now sent to xemacs-patches automatically.

  * Put subject in the :log-message-items project options. This will serve as the summary line, and then you can put whatever longer description you want on the lines below it.

That's it. Patcher generates the ChangeLog entries and performs the local commit. I just finish by pushing by hand. Maybe Patcher could also do that for me one day...