oracular (3) Dist::Zilla::Plugin::ChangelogFromGit.3pm.gz
NAME
Dist::Zilla::Plugin::ChangelogFromGit - Write a Changes file from a project's git log.
VERSION
version 0.017
SYNOPSIS
Here's an example dist.ini section showing all the current options and their default values.
[ChangelogFromGit]
max_age = 365
tag_regexp = ^v(\d+\.\d+)$
file_name = CHANGES
wrap_column = 74
debug = 0
Variables don't need to be set to their default values. This is equivalent to the configuration above.
[ChangelogFromGit]
DESCRIPTION
This Dist::Zilla plugin turns a project's git commit log into a change log file. It's better than simply
running `git log > CHANGES` in at least two ways. First, it understands release tags, and it uses them
to group changes by release. Second, it reformats the changes to make them easier to read. And third,
subclasses can change some or all of the reformatting to make change logs even easier to read.
See this project's CHANGES file for sample output. Yes, this project uses itself to generate its own
change log. Why not?
CONFIGURATION / PUBLIC ATTRIBUTES
As seen in the "SYNOPSIS", this plugin has a number of public attributes that may be set using dist.ini
configuration variables.
max_age = INTEGER
The "max_age" configuration variable limits the age of releases to be included in the change log. The
default is to include releases going back about a year. To include about two years, one would double the
default value:
[ChangelogFromGit]
max_age = 730
"max_age" is intended to limit the size of change logs for large, long-term projects that don't want to
include the entire, huge commit history in every release.
min_releases = INTEGER
"min_releases" sets the minimum number of releases that should be included. It defaults to 1 so that at
least the current release is added, regardless of "max_age".
[ChangelogFromGit]
min_releases = 5
max_releases = INTEGER
c<max_releases> allows you limit the number of releases included. "max_age" will still be the limiting
factor if it contains fewer releases than the max specified.
[ChangelogFromGit]
max_releases = 15
tag_regexp = REGULAR_EXPRESSION
"tag_regexp" sets the regular expression that detects which tags mark releases. It also extracts the
version numbers from these tags using a regular expression back reference or capture. For example, a
project's release tags might match 'release-1.000', 'release-1.001', etc. This "tag_regexp" will find
them and extract their versions.
[ChangelogFromGit]
tag_regexp = ^release-(\d+.*)$
There is no single standard format for release tags. "tag_regexp" defaults to the author's convention.
It will most likely need to be changed.
file_name = STRING
"file_name" sets the name of the change log that will be written. It defaults to "CHANGES", but some
people may prefer "Changes", "Changelog", or something else.
[ChangelogFromGit]
file_name = Changes
wrap_column = INTEGER
Different contributors tend to use different commit message formats, which can be disconcerting to the
typographically aware release engineer. "wrap_column" sets the line length to which all commit messages
will be re-wrapped. It's 74 columns by default. If this is too short:
[ChangelogFromGit]
wrap_column = 78
debug = BOOLEAN
Developers are people, too. The "debug" option enables some noisy runtime tracing on STDERR.
[ChangelogFromGit]
debug = 1
exclude_message = REGULAR_EXPRESSION
"exclude_message" sets a regular expression which discards matching commit messages. This provides a way
to exclude commit messages such as 'forgot to include file X' or 'typo'. The regular expression is case
sensitive.
[ChangelogFromGit]
exclude_message = ^(forgot|typo)
"include_message" can be used to do the opposite: exclude all changes except ones that match a regular
expression. Using both at once is liable to generate empty change logs.
include_message = REGULAR_EXPRESSION
"include_message" does the opposite of "exclude_message": it sets a regular expression which commit
messages must match in order to be included in the Changes file. This means that when making a commit
with a relevant message, you must include text that matches the regular expression pattern to have it
included in the Changes file. All other commit messages are ignored.
The regular expression is case sensitive.
[ChangelogFromGit]
include_message = ^Major
Using both "include_message" and "exclude_message" at the same time will most likely result in empty
change logs.
HOW IT WORKS
Dist::Zilla::ChangelogFromGit collects the tags matching "tag_regexp" that are not older than "max_age"
days old. These are used to identify and time stamp releases. Each release is encapsulated into a
Software::Release object.
Git::Repository::Log::Iterator is used to collect the changes prior to each release but after the
previous release. Change log entries are added to their respective Software::Release objects.
"$self->render_changelog()" is called after all the relevant releases and changes are known. It must
return the rendered change log as a string. That string will be used as the content for a
Dist::Zilla::File::InMemory object representing the new change log.
SUBCLASSING FOR NEW FORMATS
Dist::Zilla::ChangelogFromGit implement about a dozen methods to render the various parts of a change
log. Subclasses may override or augment any or all of these methods to alter the way change logs are
rendered.
All methods beginning with "render" return strings that will be incorporated into the change log.
Methods that will not contribute to the change log must return empty strings.
Rendering Entire Change Logs
Methods beginning with "render_changelog" receive no parameters other than $self. Everything they need
to know about the change log is included in the object's attributes: "wrap_column", "releases",
"skipped_release_count", "earliest_date".
render_changelog
render_changelog() returns the text of the entire change log. By default, the change log is built from a
header, zero or more releases, and a footer.
sub render_changelog {
my $self = shift();
return(
$self->render_changelog_header() .
$self->render_changelog_releases() .
$self->render_changelog_footer()
);
}
render_changelog_header
render_changelog_header() renders some text that introduces the reader to the change log.
sub render_changelog_header {
my $self = shift();
my $header = (
"Changes from " . $self->format_datetime($self->earliest_date()) .
" to present."
);
return $self->surround_line("=", $header) . "\n";
}
render_changelog_releases
render_changelog_releases() iterates through each release, calling upon $self to render them one at a
time.
sub render_changelog_releases {
my $self = shift();
my $changelog = '';
RELEASE: foreach my $release (reverse $self->all_releases()) {
next RELEASE if $release->has_no_changes();
$changelog .= $self->render_release($release);
}
return $changelog;
}
render_changelog_footer
render_changelog_footer() tells the reader that the change log is over. Normally the end of the file is
sufficient warning, but a truncated change log is friendlier when the reader knows what they're missing.
sub render_changelog_footer {
my $self = shift();
my $skipped_count = $self->skipped_release_count();
my $changelog_footer;
if ($skipped_count) {
my $releases = "release" . ($skipped_count == 1 ? "" : "s");
$changelog_footer = (
"Plus $skipped_count $releases after " .
$self->format_datetime($self->earliest_date()) . '.'
);
}
else {
$changelog_footer = "End of releases.";
}
return $self->surround_line("=", $changelog_footer);
}
Rendering Individual Releases
Methods beginning with "render_release" receive $self plus one additional parameter: a Software::Release
object encapsulating the release and its changes. See Software::Release to learn the information that
object encapsulates.
render_release
render_release() is called upon to render a single release. In the change log, a release consists of a
header, one or more changes, and a footer.
sub render_release {
my ($self, $release) = @_;
return(
$self->render_release_header($release) .
$self->render_release_changes($release) .
$self->render_release_footer($release)
);
}
render_release_header
render_release_header() introduces a release.
sub render_release_header {
my ($self, $release) = @_;
my $version = $release->version();
$version = $self->zilla()->version() if $version eq 'HEAD';
my $release_header = (
$self->format_release_tag($release->version()) . ' at ' .
$self->format_datetime($release->date())
);
return $self->surround_line("-", $release_header) . "\n";
}
render_release_changes
render_release_changes() iterates through the changes associated with each Software::Release object. It
calls upon render_change() to render each change.
sub render_release_changes {
my ($self, $release) = @_;
my $changelog = '';
foreach my $change (@{ $release->changes() }) {
$changelog .= $self->render_change($release, $change);
}
return $changelog;
}
render_release_footer
render_release_footer() may be used to divide releases. It's not used by default, but it's
implemented for completeness.
sub render_release_footer {
my ($self, $release) = @_;
return '';
}
Rendering Individual Changes
Methods beginning with "render_change" receive two parameters in addition to $self: a Software::Release
object encapsulating the release containing this change, and a Software::Release::Change object
encapsulating the change itself.
render_change
render_change() renders a single change, which is the catenation of a change header, change message, and
footer.
sub render_change {
my ($self, $release, $change) = @_;
return(
$self->render_change_header($release, $change) .
$self->render_change_message($release, $change) .
$self->render_change_footer($release, $change)
);
}
render_change_header
render_change_header() generally renders identifying information about each change. This method's
responsibility is to produce useful information in a pleasant format.
sub render_change_header {
my ($self, $release, $change) = @_;
use Text::Wrap qw(fill);
local $Text::Wrap::huge = 'wrap';
local $Text::Wrap::columns = $self->wrap_column();
my @indent = (" ", " ");
return(
fill(
" ", " ",
'Change: ' . $change->change_id
) .
"\n" .
fill(
" ", " ",
'Author: ' . $change->author_name.' <'.$change->author_email.'>'
) .
"\n" .
fill(
" ", " ",
'Date : ' . $self->format_datetime($change->date())
) .
"\n\n"
);
}
render_change_message
render_change_message() renders the commit message for the change log.
sub render_change_message {
my ($self, $release, $change) = @_;
use Text::Wrap qw(fill);
return '' if $change->description() =~ /^\s/;
local $Text::Wrap::huge = 'wrap';
local $Text::Wrap::columns = $self->wrap_column();
return fill(" ", " ", $change->description) . "\n";
}
render_change_footer
render_change_footer() returns summary and/or divider text for the change.
sub render_change_footer {
my ($self, $release, $change) = @_;
return "\n";
}
Formatting Data
Dist::Zilla::Plugin::ChangelogFromGit includes a few methods to consistently format certain data types.
format_datetime
format_datetime() converts the DateTime objects used internally into friendly, human readable dates and
times for the change log.
sub format_datetime {
my ($self, $datetime) = @_;
return $datetime->strftime("%F %T %z");
}
format_release_tag
format_release_tag() turns potentially cryptic release tags into friendly version numbers for the change
log. By default, it also replaces the 'HEAD' version with the current version being released. This
accommodates release managers who prefer to tag their distributions after releasing them.
sub format_release_tag {
my ($self, $release_tag) = @_;
return 'version ' . $self->zilla()->version() if $release_tag eq 'HEAD';
my $tag_regexp = $self->tag_regexp();
$release_tag =~ s/$tag_regexp/version $1/;
return $release_tag;
}
surround_line
surround_line() will surround a line of output with lines of dashes or other characters. It's used to
help heading stand out. This method takes two strings: a character (or string) that will repeat to fill
surrounding lines, and the line to surround. It returns a three-line string: the original line preceded
and followed by surrounding lines.
sub surround_line {
my ($self, $character, $string) = @_;
my $surrounder = substr(
($character x (length($string) / length($character) + 1)),
0,
length($string)
);
return "$surrounder\n$string\n$surrounder\n";
}
INTERNAL ATTRIBUTES
Dist::Zilla::Plugin::ChangelogFromGit accumulates useful information into a few internal attributes.
These aren't intended to be configured by dist.ini, but they are important for rendering change logs.
earliest_date
earliest_date() contains a DateTime object that represents the date and time of the earliest release to
include. It's initialized as midnight for the date max_age() days ago.
releases
releases() contains an array reference of Software::Release objects that will be included in the change
log.
all_releases
all_releases() returns a list of the Software::Release objects that should be included in the change log.
It's a friendly equivalent of "@{$self->releases()}".
get_release
get_release() returns a single release by index. The first release in the change log may be retrieved as
"$self->get_release(0)".
releae_count
release_count() returns the number of Software::Release objects in the "releases" attribute.
sort_releases
sort_releases() sorts the Software::Release objects in the releases() using some comparator. For
example, to sort releases in time order:
$self->sort_releases(
sub {
DateTime->compare( $_[0]->date(), $_[1]->date() )
}
);
skipped_release_count
skipped_release_count() contains the number of releases truncated by max_age(). The default
render_changelog_footer() uses it to display the number of changes that have been omitted from the log.
INTERNAL METHODS
Dist::Zilla::Plugin::ChangelogFromGit implements a couple of "unpublished" methods. These are not
intended for general use.
gather_files()
Find all release tags back to the earliest changelog date.
Add a virtual release for the most recent change in the repository. This lets us include changes after
the last releases, up to "HEAD".
rungit()
A wrapper to run git commands.
Subversion and CVS
This plugin is almost entirely a copy-and-paste port of a command-line tool I wrote a while ago. I also
have tools to generate similar change logs for CVS and Subversion projects. I'm happy to contribute that
code to people interested in creating Dist::Zilla plugins for other version control systems.
We should also consider abstracting the formatting code out to a role so that it can be shared among
different plugins.
BUGS
The documentation includes copies of the renderer methods. This increases technical debt, since changes
to those methods must also be copied into the documentation. Rocco needs to finish Pod::Plexus and use
it here to simplify maintenance of the documentation.
Collecting all releases and changes before rendering the change log may be considered harmful for
extremely large projects. If someone thinks they can generate change logs incrementally, their
assistance would be appreciated.
AUTHORS
Rocco Caputo <rcaputo@cpan.org> - Initial release, and ongoing management and maintenance. Cory G. Watson <gphat@cpan.org> - Made formatting extensible and overridable.
COPYRIGHT AND LICENSE
This software is copyright (c) 2010-2018 by Rocco Caputo.
This is free software; you may redistribute it and/or modify it under the same terms as the Perl 5
programming language itself.