NAME
Perl::Metric::Basic - Provide basic software metrics
SYNOPSIS
# first construct a PPI::Document object to pass in
my $document = PPI::Document->load("t/lib/Acme.pm");
# then retrieve metrics on the document
my $m = Perl::Metric::Basic->new;
my $metric = $m->measure($document);
# $metric will consist of something like:
# 'Acme' => {
# 'new' => {
# 'blank_lines' => 1,
# 'comments' => 1,
# 'lines' => 7,
# 'lines_of_code' => 6,
# 'numbers' => 0,
# 'numbers_unique' => 0,
# 'operators' => 3,
# 'operators_unique' => 2,
# 'symbols' => 5,
# 'symbols_unique' => 2,
# 'words' => 7,
# 'words_unique' => 6
# },
# ...
DESCRIPTION
When constructing software one often produces code of vastly differing
quality. The Perl::Metric::Basic module leverages the PPI module to
provide some interesting software metrics for Perl code, mostly
measuring size and maintainability.
A metric is some sort of measurement which is intended to help you make
a decision about a piece of code. There aren't any hard rules about
metrics, but the ones provided should allow you to make decisions about
modules or subroutines which are outliers. Abnormal measurements in a
subroutine are a warning sign that you should reexamine that routine,
checking for unusually low quality.
This module uses the PPI module, and thus can parse Perl code without
evaluating it.
If you're interested in software metrics, I highly recommend "Code
Complete" (Second Edition) by Steve McConnel (Microsoft Press).
METHODS
new()
The new() method is the constructor:
my $m = Perl::Metric::Basic->new;
measure()
The measure() method measures some metrics and returns a hash reference.
Files in Perl can contain more than one package, and it is interesting
to seperate metrics by package. The key for the hash reference is the
name of the package, and the value is another hash reference.
Perl packages are seperated into subroutines, and it is interesting to
seperate metrics by subroutine. The key for the second hash reference is
the name of the subroutine, and the value is another hash reference
containing metrics.
There are various metrics applied to the subroutine. The key for the
third hash reference is the name of the metric, and the value is the
value of the metric. The metrics are:
blank_lines
The number of blank code lines.
comments
The number of lines containing comments.
lines
The total number of lines.
lines_of_code
The number of lines of code.
numbers
The total number of numbers used (eg "$z = 42 * 3" would have 2
numbers).
numbers_unique
The number of unique numbers used (eg "$z = 2*$x + 2*$y" would have
1 unique number).
operators
The total number of operators used.
operators_unique
The number of unique operators used.
symbols
The total number of symbols used (eg "$z = $x*$x + $y*$y" would have
5 symbols).
symbols_unique
The number of unique symbols used (eg "$z = $x*$x + $y*$y" would
have 3 unique symbols).
words
The total number of words (operators) used.
words_unique
The number of unique words used.
NOTES
Currently the code only works for object-oriented classes, not scripts.
AUTHOR
Leon Brocard <
[email protected]>
COPYRIGHT
Copyright (C) 2004, Leon Brocard
This module is free software; you can redistribute it or modify it under
the same terms as Perl itself.
