quick question on modules

[perlaintdead]

if you load a module like: use something::or::other qw(funt); will it use less memory than just: use something::or::other;

[LanX]

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.

[Corion]

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

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.

[vinoth.ree]

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

[Anonymous Monk]

The question was "will it use less memory" not "what is the difference between ..."

[Anonymous Monk]

The question was "will it use less memory" not "what is the difference between ..."

And then?

[perlaintdead]

/\ thanks to all above

[Anonymous Monk]

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.

[dsheroh]

An important point alluded to, but never explicitly stated, by the earlier answers: The only difference is in which symbols are aliased into the useing 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 user's namespace, so it's not going to be a significant difference.

¹ If the used 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 used.