Loading a module at runtime

jhisey has asked for the wisdom of the Perl Monks concerning the following question:

I swear I've done this before but can't get it to work now. I'm trying to load a module at runtime based on a variable. Previously, I'm positive I did it using eval but for some reason it's not working for me. For example:

if ($DEBUG) {
  eval { use SOAP::Lite +trace => 'debug'; };
}
else {
  eval { use SOAP::Lite; };
}
[download]

One thing that is different now then last time I did this is this is inside of a .pm itself. Would that have any bearing on when the SOAP::Lite module gets loaded? It always loads with +trace on in this scenario. Thanks!

Comment on Loading a module at runtime Download Code

Replies are listed 'Best First'.
Re: Loading a module at runtime by runrig (Abbot) on May 04, 2011 at 22:53 UTC
Read the docs for eval. With `eval { BLOCK }` the code in BLOCK is parsed at 'compile' time. With `eval $string` the code in $string can not be parsed until 'runtime'. use is executed before runtime. Perhaps your evals worked when the contents were strings. Perhaps you want to use require (update: I see you have an import list...That would require `SOAP::Lite->import(@list)`. And you probably want to wrap this logic in a `BEGIN {}` block.	[reply] [d/l] [select]
Re^2: Loading a module at runtime by Anonymous Monk on May 05, 2011 at 02:46 UTC
Just an FYI, this is how I finally got it working: `if ($DEBUG) { eval "use SOAP::Lite; SOAP::Lite->import(+trace => 'debug');"; } else { eval "use SOAP::Lite;"; }` [download]	[reply] [d/l]
Re^3: Loading a module at runtime by Anonymous Monk on May 05, 2011 at 03:22 UTC
`use SOAP::Lite; use if $DEBUG, qw[ SOAP::Lite +trace debug ];` [download]	[reply] [d/l]
Re: Loading a module at runtime by wind (Priest) on May 05, 2011 at 00:36 UTC
As documented in use, require and accessing import directly should get what you want. The BEGIN block is optional depending on where you want this done: `BEGIN { require SOAP::Lite; SOAP::Lite->import($DEBUG ? qw(+trace debug) : ()); }` [download]	[reply] [d/l]