I put together this code to help migrating Perl scripts from one environment to another. The scripts are mostly CGIs, and I found it annoying and time consuming to either
run the scripts to see what breaks
read through each script manually
. Using this little script you can check whether all needed modules are available.
Comments and suggestions are appreciated as always...
Update: Changed the logic in my if statement to reflect podmaster's CB suggestion...
my $filename=shift || &help; # command line argument is perl script to
my @modules; # array of 'use' statements from code we are checking
open (IN,$filename) or die "couldn't open $filename for processing: $!
if ((/^use/) and not (/strict/ || /warnings/))
for my $code (@modules)
my (undef,$library)=split(/ /,$code); # get the module name
$library=~s/;//; # clean up the name
warn "couldn't load $library: $@","\n";
print "$library looks ok\n";
This script finds all the "use" statements loading modules in the targ
file (specified as a command line argument) and attempts to load them.
If there are problems loading the module, the error mesage returned is
Good idea, nice effort, and probably the same route I'd take if I hadn't picked up various details during my Perl efforts. However, there are better ways to do this. Regexing sources is easy to break and your script cannot conveniently report recursive dependencies where a module a script depends on relies on other modules itself.
It's not very complicated once you know how loading modules works: basically, the @INC array contains all the paths to any directories where perl should look for modules.
Usually, these are only strings, but you can also put a reference to a subroutine in there; when perl is searching for modules, it will call that routine if it hasn't found the module by one of the paths that appear before it in the array. Along with various parameters passed to such a routine is the module's path in the second parameter which is in this case copied to $_ in order to massage it to my liking.
Because this is a module, the code in its main body gets executed as soon as the module is loaded, at compile time, and therefor gets to modify the @INC array before anything else has happened.