Question

I am currently working on a roughly 15 years old web application.

It contains mainly CGI perl scripts with HTML::Template templates.

It has over 12 000 files and roughly 260 MB of total code. I estimate that no more than 1500 perl scripts are needed and I want to get rid of all the unused code.

There are practically no tests written for the code.

My questions are:

• Are you aware of any CPAN module that can help me get a list of only used and required modules?
• What would be your approach if you’d want to get rid of all the extra code?

I was thinking at the following approaches:

• try to override the use and require perl builtins with ones that output the loaded file name in a specific location
• override the warnings and/or strict modules import function and output the file name in the specific location
• study the Devel::Cover perl module and take the same approach and analyze the code when doing manual testing instead of automated tests
• replace the perl executable with a custom one, which will log each name of file it reads (I don’t know how to do that yet)
• some creative use of lsof (?!?)

Answer 1

Devel::Modlist may give you what you need, but I have never used it.

The few times I have needed to do somehing like this I have opted for the more brute force approach of inspecting %INC at the end the program.

END {
    open my $log_fh, ...;
    print $log_fh "$_\n" for sort keys %INC;
}