Ovid

You may have seen or played with the Smalltalk browser before:

If you have, you'd love it. It makes it trivial to browse through, visualize and manage a project. However, we don't have anything like this for Perl. brian d foy has tried to create a Perl browser (with code on github), but that's the only significant effort in this direction I've seen. Padre has a ticket for a subset of this functionality, but as far as I can tell, it has the same limitation as brian's approach (please correct me if I'm wrong): it's file-based.

Given Perl's dynamic nature, what if we ditched the file-based heuristics and actually examine running code? I've been thinking about this.

My idea is as follows (pseudo-code):

package My::Project::Image;
use Moose;
with qw(Does::Perl::Image);

# any extra code, if needed, but the above should be enough
has dependencies => ( is => 'ro', isa => 'Str', required => 1 );

sub stop {
    # any needed cleanup to stop an image
}

And then to use the image, it would be something like this:

#!/usr/bin/env perl
use Modern::Perl
use My::Project::Image;
use My::Project;

my $image = My::Project::Image->new({
    lib   => 'lib/',
    tests => 't/',
    deps  => 'deps/lib',
    start => sub { My::Project->new },
    stop  => sub { shift->image->stop },
});

The idea is that you tell the image where to find the lib directory, the tests, and any extra information relevant to your image and then you pass it an init subref which runs some code to load the image in memory. In other words, you run code and we inspect what's actually in memory rather than use heuristics to analyse files.

There are several obstacles to this approach.

• You can't disambiguate between methods and subroutines.
• You can't disambiguate between classes and instances (heck, classes and module distinctions would get tossed).
• The develop should be aware of side-effects from BEGIN blocks or similar issues.
• Altering @ISA, diddling with namespaces and similar trickery could lead to an out-of-date image.

I think, perhaps, that this should spawn a separate thread and keep reloading an image whenever a given event occurs (you change a file, perhaps) and maybe have a SQLite backend to store image data. If the entire project was based on Moose, much of the utility of this would go away, but Moose doesn't help you when you're working with procedural code.

Also, integration with Devel::CoverX::Covered and similar tools would be useful.

Would something like this be feasible? Would it be worthwhile? I fear that Perl's ad-hoc OO system would limit much of the utility outside of Moose.