NAME

       App::FatPacker::Trace - Tracing module usage using compilation checking

SYNOPSIS

           # open STDERR for writing
           # will be like: open my $fh, '>', '&STDERR'...
           perl -MApp::FatPacker::Trace=>&STDERR myscript.pl

           # open a file for writing
           # will be like: open my $fh, '>>', 'fatpacker.trace'
           perl -MApp::FatPacker::Trace=>>fatpacker.trace myscript.pl

DESCRIPTION

       This module allows tracing the modules being used by your code. It does that using clever
       trickery using the "import" method, the "CHECK" block and B's "minus_c" function.

       When App::FatPacker::Trace is being used, the import() method will call "B::minus_c" in
       order to set up the global compilation-only flag perl (the interpreter) has. This will
       prevent any other code from being run.

       Then in the "CHECK" block which is reached at the end of the compilation phase (see
       perlmod), it will gather all modules that have been loaded, using %INC, and will write it
       to a file or to STDERR, determined by parameters sent to the "import" method.

METHODS

   import
       This method gets run when you just load App::FatPacker::Trace. It will note the current
       %INC and will set up the output to be written to, and raise the compilation-only flag,
       which will prevent anything from being run past that point. This flag cannot be unset, so
       this is most easily run from the command line as such:

           perl -MApp::FatPacker::Trace [...]

       You can control the parameters to the import using an equal sign, as such:

           # send the parameter "hello"
           perl -MApp::FatPacker::Trace=hello [...]

           # send the parameter ">&STDERR"
           perl -MApp::FatPacker::Trace=>&STDERR [...]

       The import method accepts a first parameter telling it which output to open and how. These
       are both sent in a single parameter.

           # append to mytrace.txt
           perl -MApp::FatPacker::Trace=>>mytrace.txt myscript.pl

           # write to STDERR
           perl -MApp::FatPacker::Trace=>&STDERR myscript.pl

       The import method accepts additional parameters of extra modules to load.  It will then
       add these modules to the trace. This is helpful if you want to explicitly indicate
       additional modules to trace, even if they aren't used in your script. Perhaps you're
       conditionally using them, perhaps they're for additional features, perhaps they're loaded
       lazily, whatever the reason.

           # Add Moo to the trace, even if you don't trace it in myscript.pl
           perl -MApp::FatPacker::Trace=>&STDERR,Moo myscript.pl