Enhance gitdiffs help text

mercurial/help.py

@@ -1,248 +1,254 b''
 # help.py - help data for mercurial
 #
 # Copyright 2006 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
 from i18n import _
 
 helptable = (
     (["dates"], _("Date Formats"),
      _(r'''
     Some commands allow the user to specify a date:
     backout, commit, import, tag: Specify the commit date.
     log, revert, update: Select revision(s) by date.
 
     Many date formats are valid. Here are some examples:
 
     "Wed Dec 6 13:18:29 2006" (local timezone assumed)
     "Dec 6 13:18 -0600" (year assumed, time offset provided)
     "Dec 6 13:18 UTC" (UTC and GMT are aliases for +0000)
     "Dec 6" (midnight)
     "13:18" (today assumed)
     "3:39" (3:39AM assumed)
     "3:39pm" (15:39)
     "2006-12-06 13:18:29" (ISO 8601 format)
     "2006-12-6 13:18"
     "2006-12-6"
     "12-6"
     "12/6"
     "12/6/6" (Dec 6 2006)
 
     Lastly, there is Mercurial's internal format:
 
     "1165432709 0" (Wed Dec 6 13:18:29 2006 UTC)
 
     This is the internal representation format for dates. unixtime is
     the number of seconds since the epoch (1970-01-01 00:00 UTC). offset
     is the offset of the local timezone, in seconds west of UTC (negative
     if the timezone is east of UTC).
 
     The log command also accepts date ranges:
 
     "<{date}" - on or before a given date
     ">{date}" - on or after a given date
     "{date} to {date}" - a date range, inclusive
     "-{days}" - within a given number of days of today
     ''')),
 
     (["patterns"], _("File Name Patterns"),
      _(r'''
     Mercurial accepts several notations for identifying one or more
     files at a time.
 
     By default, Mercurial treats filenames as shell-style extended
     glob patterns.
 
     Alternate pattern notations must be specified explicitly.
 
     To use a plain path name without any pattern matching, start a
     name with "path:".  These path names must match completely, from
     the root of the current repository.
 
     To use an extended glob, start a name with "glob:".  Globs are
     rooted at the current directory; a glob such as "*.c" will match
     files ending in ".c" in the current directory only.
 
     The supported glob syntax extensions are "**" to match any string
     across path separators, and "{a,b}" to mean "a or b".
 
     To use a Perl/Python regular expression, start a name with "re:".
     Regexp pattern matching is anchored at the root of the repository.
 
     Plain examples:
 
     path:foo/bar   a name bar in a directory named foo in the root of
                    the repository
     path:path:name a file or directory named "path:name"
 
     Glob examples:
 
     glob:*.c       any name ending in ".c" in the current directory
     *.c            any name ending in ".c" in the current directory
     **.c           any name ending in ".c" in the current directory, or
                    any subdirectory
     foo/*.c        any name ending in ".c" in the directory foo
     foo/**.c       any name ending in ".c" in the directory foo, or any
                    subdirectory
 
     Regexp examples:
 
     re:.*\.c$      any name ending in ".c", anywhere in the repository
 
     ''')),
 
     (['environment', 'env'], _('Environment Variables'),
      _(r'''
 HG::
     Path to the 'hg' executable, automatically passed when running hooks,
     extensions or external tools. If unset or empty, an executable named
     'hg' (with com/exe/bat/cmd extension on Windows) is searched.
 
 HGEDITOR::
     This is the name of the editor to use when committing. See EDITOR.
 
     (deprecated, use .hgrc)
 
 HGENCODING::
     This overrides the default locale setting detected by Mercurial.
     This setting is used to convert data including usernames,
     changeset descriptions, tag names, and branches. This setting can
     be overridden with the --encoding command-line option.
 
 HGENCODINGMODE::
     This sets Mercurial's behavior for handling unknown characters
     while transcoding user inputs. The default is "strict", which
     causes Mercurial to abort if it can't translate a character. Other
     settings include "replace", which replaces unknown characters, and
     "ignore", which drops them. This setting can be overridden with
     the --encodingmode command-line option.
 
 HGMERGE::
     An executable to use for resolving merge conflicts. The program
     will be executed with three arguments: local file, remote file,
     ancestor file.
 
     (deprecated, use .hgrc)
 
 HGRCPATH::
     A list of files or directories to search for hgrc files.  Item
     separator is ":" on Unix, ";" on Windows.  If HGRCPATH is not set,
     platform default search path is used.  If empty, only .hg/hgrc of
     current repository is read.
 
     For each element in path, if a directory, all entries in directory
     ending with ".rc" are added to path.  Else, element itself is
     added to path.
 
 HGUSER::
     This is the string used for the author of a commit.
 
     (deprecated, use .hgrc)
 
 EMAIL::
     If HGUSER is not set, this will be used as the author for a commit.
 
 LOGNAME::
     If neither HGUSER nor EMAIL is set, LOGNAME will be used (with
     '@hostname' appended) as the author value for a commit.
 
 VISUAL::
     This is the name of the editor to use when committing. See EDITOR.
 
 EDITOR::
     Sometimes Mercurial needs to open a text file in an editor
     for a user to modify, for example when writing commit messages.
     The editor it uses is determined by looking at the environment
     variables HGEDITOR, VISUAL and EDITOR, in that order. The first
     non-empty one is chosen. If all of them are empty, the editor
     defaults to 'vi'.
 
 PYTHONPATH::
     This is used by Python to find imported modules and may need to be set
     appropriately if Mercurial is not installed system-wide.
     ''')),
 
     (['revs', 'revisions'], _('Specifying Single Revisions'),
      _(r'''
     Mercurial accepts several notations for identifying individual
     revisions.
 
     A plain integer is treated as a revision number. Negative
     integers are treated as offsets from the tip, with -1 denoting the
     tip.
 
     A 40-digit hexadecimal string is treated as a unique revision
     identifier.
 
     A hexadecimal string less than 40 characters long is treated as a
     unique revision identifier, and referred to as a short-form
     identifier. A short-form identifier is only valid if it is the
     prefix of one full-length identifier.
 
     Any other string is treated as a tag name, which is a symbolic
     name associated with a revision identifier. Tag names may not
     contain the ":" character.
 
     The reserved name "tip" is a special tag that always identifies
     the most recent revision.
 
     The reserved name "null" indicates the null revision. This is the
     revision of an empty repository, and the parent of revision 0.
 
     The reserved name "." indicates the working directory parent. If
     no working directory is checked out, it is equivalent to null.
     If an uncommitted merge is in progress, "." is the revision of
     the first parent.
     ''')),
 
     (['mrevs', 'multirevs'], _('Specifying Multiple Revisions'),
      _(r'''
     When Mercurial accepts more than one revision, they may be
     specified individually, or provided as a continuous range,
     separated by the ":" character.
 
     The syntax of range notation is [BEGIN]:[END], where BEGIN and END
     are revision identifiers. Both BEGIN and END are optional. If
     BEGIN is not specified, it defaults to revision number 0. If END
     is not specified, it defaults to the tip. The range ":" thus
     means "all revisions".
 
     If BEGIN is greater than END, revisions are treated in reverse
     order.
 
     A range acts as a closed interval. This means that a range of 3:5
     gives 3, 4 and 5. Similarly, a range of 4:2 gives 4, 3, and 2.
     ''')),
 
-    (['gitdiffs'], _('Using git Diffs'),
+    (['gitdiffs'], _('Git Extended Diff Format'),
      _(r'''
-    In several places, Mercurial supports two separate variations on
-    the unified diff format: normal diffs, as are de facto standardized
-    by GNU's patch utility, and git diffs, invented for the git VCS.
+    Mercurial's default format for showing changes between two versions
+    of a file is compatible to the unified format of GNU diff, which
+    can be used by GNU patch and many other standard tools.
 
-    The git diff format is an addition of some information to the normal
-    diff format, which allows diff to convey changes in file permissions
-    as well as the creation, deletion, renaming and copying of files, as
-    well as diffs for binary files (unsupported by standard diff),
-    operations which are very useful to modern version control systems
-    such as Mercurial, in trying to faithfully replay your changes.
+    While this de facto standardized format is often enough, there are
+    cases where additional change information should be included in the
+    generated diff file:
+
+     - executable status
+     - copy or rename information
+     - changes in binary files
+     - creation or deletion of empty files
 
-    In building Mercurial, we made a choice to support the git diff
-    format, but we haven't made it the default. This is because for a
-    long time, the format for unified diffs we usually use has been
-    defined by GNU patch, and it doesn't (yet) support git's extensions
-    to the diff format. This means that, when extracting diffs from a
-    Mercurial repository (through the diff command, for example), you
-    must be careful about things like file copies and renames (file
-    creation and deletion are mostly handled fine by the traditional
-    diff format, with some rare edge cases for which the git extensions
-    can be used). Mercurial's internal operations (like push and pull)
-    are not affected by these differences, because they use a different,
-    binary format for communicating changes.
+    Mercurial adopted the extended diff format which was invented for
+    the git VCS to support above features.
+
+    The git extended diff format is not produced by default, because
+    there are only very few tools (yet) which understand the additional
+    information provided by them.
 
-    To use git diffs, use the --git option for relevant commands, or
-    enable them in a hgrc, setting 'git = True' in the [diff] section.
+    This means that, when generating diffs from a Mercurial repository
+    (e.g. with "hg export"), you should be careful about things like
+    file copies and renames or other things mentioned above, because
+    when applying a standard diff to a different repository, this extra
+    information is lost. Mercurial's internal operations (like push and
+    pull) are not affected by this, because they use a different, binary
+    format for communicating changes.
+
+    To make Mercurial produce the git extended diff format, use the
+    --git option available for many commands, or set 'git = True' in the
+    [diff] section of your hgrc. You do not need to set this option when
+    importing diffs in this format or using them in the mq extension.
     ''')),
 )