[Israel.pm] use and require

Levenglick Dov-RM07994 RM07994 at freescale.com
Sun Mar 20 23:17:01 PDT 2011


Taking this 17 steps back, although there is extensive documentation I have yet to fully grasp the difference between use and require. I know it well enough to explain to people who know less about perl than I do - but I don't truly understand.

Would someone, without quoting perldoc or sending me to RTFM, please explain the mechanics of the difference; all ramifications included. 

 
Best Regards,
Dov Levenglick
SmartDSP OS Development Leader
-----Original Message-----
From: perl-bounces at perl.org.il [mailto:perl-bounces at perl.org.il] On Behalf Of Shmuel Fomberg
Sent: Sunday, March 20, 2011 05:15
To: Perl in Israel
Subject: Re: [Israel.pm] use and require

On 2011/03/13 19:45, sawyer x wrote:
>
>     Whenever I see 'require' used instead of 'use', I expect problems
>     in the
>     module-dependency tree.
>
>
> I think there are benefits to both. It depends, as always, on your needs.
>
> If you have a healthy build process, you can use "require" instead of 
> "use" when you want to allow some features to be lazy, and that's very 
> useful. You can also allow loading two different versions of the same 
> mechanism, depending on some logic. If you have this, load that one, 
> if not, load this one. Imagine Mouse only uses Moose if it's already 
> loaded, saving you a ton on compile-time.
While you are right, I think that these 'require' statements should be 
in very specific places. plugins finding and loading code, dynamic 
feature loading, and so on.
but not littered through the code.
Especially the main perl file, should 'use' all the modules that are 
known to be needed for running it. no point leaving it to later point of 
time.

Shmuel.
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