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UML::Class::Simple - Render simple UML class diagrams, by loading the code


This document describes UML::Class::Simple 0.22 released by 18 December 2016.


    use UML::Class::Simple;

    # produce a class diagram for Alias's PPI
    # which has already installed to your perl:

    @classes = classes_from_runtime("PPI", qr/^PPI::/);
    $painter = UML::Class::Simple->new(\@classes);

    # produce a class diagram for your CPAN module on the disk

    @classes = classes_from_files(['lib/', 'lib/Foo/']);
    $painter = UML::Class::Simple->new(\@classes);

    # we can explicitly specify the image size
    $painter->size(5, 3.6); # in inches

    # ...and change the default title background color:
    $painter->node_color('#ffffff'); # defaults to '#f1e1f4'

    # only show public methods and properties

    # hide all methods from parent classes



UML::Class::Simple is a Perl CPAN module that generates UML class diagrams (PNG format, GIF format, XMI format, or dot source) automatically from Perl 5 source or Perl 5 runtime.

Perl developers can use this module to obtain pretty class diagrams for arbitrary existing Perl class libraries (including modern perl OO modules based on, by only a single command. Companies can also use the resulting pictures to visualize the project hierarchy and embed them into their documentation.

The users no longer need to drag a mouse on the screen so as to draw figures themselves or provide any specs other than the source code of their own libraries that they want to depict. This module does all the jobs for them! :)

Methods created on-the-fly (in BEGIN or some such) can be inspected. Accessors created by modules Class::Accessor, Class::Accessor::Fast, and Class::Accessor::Grouped are recognized as "properties" rather than "methods". Intelligent distingishing between Perl methods and properties other than that is not provided.

You know, I was really impressed by the outputs of UML::Sequence, so I decided to find something to (automatically) get pretty class diagrams too. The images from Autodia's Graphviz backend didn't quite fit my needs when I was making some slides for my presentations.

I think most of the time you just want to use the command-line utility offered by this module (just like me). See the documentation of for details.



(See also samples/ppi_small.png in the distribution.)


(See also samples/moose_small.png in the distribution.)


(See also samples/fast.png in the distribution.)


classes_from_runtime($module_to_load, $regex?)
classes_from_runtime(\@modules_to_load, $regex?)

Returns a list of class (or package) names by inspecting the perl runtime environment. $module_to_load is the main module name to load while $regex is a perl regex used to filter out interesting package names.

The second argument can be omitted.

classes_from_files($pmfile, $regex?)
classes_from_files(\@pmfiles, $regex?)

Returns a list of class (or package) names by scanning through the perl source files given in the first argument. $regex is used to filter out interesting package names.

The second argument can be omitted.


Excludes package names via specifying one or more paths where the corresponding modules were installed into. For example:

    @classes = exclude_by_paths(\@classes, 'C:/perl/lib');

    @classes = exclude_by_paths(\@classes, '/home/foo', '/System/Library');

Filters out package names via specifying one or more paths where the corresponding modules were installed into. For instance:

    @classes = grep_by_paths(\@classes, '/home/malon', './blib/lib');

All these subroutines are exported by default.


$obj->new( [@class_names] )

Create a new UML::Class::Simple instance with the specified class name list. This list can either be constructed manually or by the utility functions classes_from_runtime and classes_from_files.


Generate PNG image file when $filename is given. It returns binary data when $filename is not given.


Generate SVG image file when $filename is given. It returns binary data when $filename is not given.


Similar to as_png, bug generate a GIF-format image. Note that, for many graphviz installations, gif support is disabled by default. So you'll probably see the following error message:

    Format: "gif" not recognized. Use one of: bmp canon cmap cmapx cmapx_np
        dia dot fig gtk hpgl ico imap imap_np ismap jpe jpeg jpg mif mp
        pcl pdf pic plain plain-ext png ps ps2 svg svgz tif tiff vml
        vmlz vtx xdot xlib

Return the internal DOM tree used to generate dot and png. The tree's structure looks like this:

    'classes' => [
                     'subclasses' => [],
                     'methods' => [],
                     'name' => 'PPI::Structure::List',
                     'properties' => []
                     'subclasses' => [
                     'methods' => [
                     'name' => 'PPI::Structure',
                     'properties' => []

You can adjust the data structure and feed it back to $obj via the set_dom method.


Set the internal DOM structure to $obj. This will be used to generate the dot source and thus the PNG/GIF images.


Return the Graphviz dot source code generated by $obj.


Set the dot source code used by $obj.


Generate XMI model file when $filename is given. It returns XML::LibXML::Document object when $filename is not given.


Copied from IPC::Cmd to test if $path is a runnable program. This code is copyright by IPC::Cmd's author.

$prog = $obj->dot_prog()

Get or set the dot program path.


$obj->size($width, $height)
($width, $height) = $obj->size

Set/get the size of the output images, in inches.

$bool = $obj->public_only

When the public_only property is set to true, only public methods or properties are shown. It defaults to false.

$bool = $obj->inherited_methods

When the inherited_methods property is set to false, then all methods, inherited from parent classes, are not shown. It defaults to true.

$color = $obj->node_color

Set/get the background color for the class nodes. It defaults to '#f1e1f4'.


When this property is set to true values, then relationships between Moose::Role packages and their consumers will be drawn in the output. Default to false.


When this property is set to false, then class methods will not be shown in the output. Default to true.


When this property is set to false, then the class inheritance relationship will not be drawn in the output. Default to false.


Please download and intall a recent Graphviz release from its home:

UML::Class::Simple requires the HTML label feature which is only available on versions of Graphviz that are newer than mid-November 2003. In particular, it is not part of release 1.10.

Add Graphviz's bin/ path to your PATH environment. This module needs its dot utility.

Grab this module from the CPAN mirror near you and run the following commands:

    perl Makefile.PL
    make test
    make install

For windows users, use nmake instead of make.

Note that it's recommended to use the cpan utility to install CPAN modules.


  • It's pretty hard to distinguish perl methods from properties (actually they're both implemented by subs in perl). Currently only accessors created by Class::Accessor, Class::Accessor::Fast, and Class::Accessor::Grouped are provided. (Thanks to the patches from Adam Lounds and Dave Howorth!) If you have any other good idea on this issue, please drop me a line ;)

  • Only the inheritance relationships are shown in the images. I believe other subtle relations may mess up the Graphviz layouter. Hence the "::Simple" suffix in this module name.

  • Unlike Autodia, at this moment only Graphviz and XMI backends are provided.

  • There's no way to recognize real perl classes automatically. After all, Perl 5's classes are implemented by packages. I think Perl 6 will make my life much easier.

  • To prevent potential naming confusion. I'm using Perl's :: namespace separator in the class diagrams instead of dot (.) chosen by the UML standard. One can argue that following UML standards is more important since people in the same team may use different programming languages, but I think it's not the case for the majority (including myself) ;-)


  • Add more unit tests.

  • Add support for more image formats, such as as_ps, as_jpg, and etc.

  • Plot class relationships other than inheritance on the user's request.

  • Provide backends other than Graphviz.

Please send me your wish list by emails or preferably via the CPAN RT site. I'll add them here or even implement them promptly if I'm also interested in your (crazy) ideas. ;-)


There must be some serious bugs lurking somewhere; if you found one, please report it to or contact the author directly.


I must thank Adam Kennedy (Alias) for writing the excellent PPI and Class::Inspector modules. uses the former to extract package names from user's .pm files or the latter to retrieve the function list of a specific package.

I'm also grateful to Christopher Malon since he has (unintentionally) motivated me to turn the original hack into this CPAN module. ;-)


You can always grab the latest version from the following GitHub repository:

It has anonymous access to all.

If you have the tuits to help out with this module, please let me know. I have a dream to keep sending out commit bits like Audrey Tang. ;-)


Yichun "agentzh" Zhang (章亦春) <>, OpenResty Inc.

Maxim Zenin <>.


Copyright (c) 2006-2016 by Yichun Zhang (章亦春), OpenResty Inc. Copyright (c) 2007-2014 by Maxim Zenin.

This library is free software; you can redistribute it and/or modify it under the same terms as perl itself, either Artistic and GPL.

SEE ALSO, Autodia, UML::Sequence, PPI, Class::Inspector, XML::LibXML.