quick question on modules

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

Replies are listed 'Best First'.
Re: quick question on modules by LanX (Saint) on Feb 01, 2013 at 09:38 UTC
Normally no! Use means that a module-function import() is called at BEGIN-time. Normally this function is inherited by Exporter module and does only an aliasing of imported functions. And aliasing costs only some bytes, not enough to be discussed. But a module author can chose to define his own import and do whatever he wants... so no general answer here. Cheers Rolf	[reply]
Re^2: quick question on modules by Corion (Patriarch) on Feb 01, 2013 at 09:47 UTC
A great counterexample is POSIX: Q:\>perl -MPOSIX -wle "print for grep {$_ =~ /$$/} `tasklist`" perl.exe 5508 Console 0 3.936 +K Q:\>perl -MPOSIX=strftime -wle "print for grep {$_ =~ /$$/} `tasklist` +" perl.exe 4904 Console 0 3.672 +K [download] POSIX.pm exports all its functions and constants by default, which costs 300K memory, while importing just the few needed functions reduces the amount of memory spent. tl; dr - just like you said, no general answer here.	[reply] [d/l]
Re: quick question on modules by vinoth.ree (Monsignor) on Feb 01, 2013 at 09:43 UTC
If you use `use something::or::other qw(funt)` this method, it will export only `funt` symbol into the caller namespace. If you use `use something::or::other` method, it will export list of symbols (subroutines and variables) of the module to be exported into the caller namespace from @EXPORT array defined in `something::or::other`	[reply] [d/l] [select]
Re^2: quick question on modules by Anonymous Monk on Feb 01, 2013 at 10:28 UTC
The question was "will it use less memory" not "what is the difference between ..."	[reply]
Re^3: quick question on modules by Anonymous Monk on Feb 01, 2013 at 10:48 UTC
The question was "will it use less memory" not "what is the difference between ..." And then?	[reply]
Re: quick question on modules by perlaintdead (Scribe) on Feb 01, 2013 at 10:03 UTC
/\ thanks to all above	[reply]
Re: quick question on modules by Anonymous Monk on Feb 01, 2013 at 13:17 UTC
I suspect that it very often comes down to how many things, that are not already used, are brought in by the module being used.	[reply]
Re: quick question on modules by dsheroh (Monsignor) on Feb 02, 2013 at 09:07 UTC
An important point alluded to, but never explicitly stated, by the earlier answers: The only difference is in which symbols are aliased into the `use`ing module. All of `something::or::other` will be compiled and kept in memory regardless of whether you only import `funt` or import all available symbols¹. The memory used to load the module's code will dwarf the memory used to alias the exported symbols into the `use`r's namespace, so it's not going to be a significant difference. ¹ If the `use`d module is built around Autoloader/AutoSplit/SelfLoader, this doesn't hold, as they allow the module to only load and compile subs on-demand instead of compiling the whole thing at program start-up. In my experience, though, this isn't done all that often, so it's probably safe to assume that any random module will be loaded in full if `use`d.	[reply] [d/l] [select]