CODEWITHSUNDEEP
perlrequireperl-module
Learning
Learning

Reputation: 219

Why LWP::UserAgent is imported by require LWP::UserAgent instead of use LWP::UserAgent?

I'm pretty new to this language but I've been using use to import a specific module before,

why LWP::UserAgent uses require to do the job as from perldoc LWP::UserAgent:

require LWP::UserAgent;

Upvotes: 2

Views: 473

Answers (3)

Kamil Dąbrowski
Kamil Dąbrowski

Reputation: 1092

For people who come from google search and looking this solutions:

For Message Error: LWP::UserAgent not found at ./apache_accesses line 86.

Solution: apt-get install libwww-perl

Upvotes: -3

ysth
ysth

Reputation: 98423

require Module::Name has the same effect as use, only at run-time, not compile-time. This is sometimes advantageous when you want to conditionally require a module. I don't think there's any particular reason for the doc to say require instead of use.

Upvotes: 0

ikegami
ikegami

Reputation: 386561

use LWP::UserAgent;

is the same as

BEGIN {
    require LWP::UserAgent;
    import LWP::UserAgent;
}

If require LWP::UserAgent; is acceptable, that goes to show that import does nothing for LWP::UserAgent. Maybe the point of the documentation's use of require is to subtly imply this?

The only difference between require LWP::UserAgent; and use LWP::UserAgent; is thus when require is executed. For the former, it happens after the entire file has been compiled. For the latter, it occurs as soon as that statement has been compiled. In practical terms, there's no much difference for object-oriented modules.

Personally, I use

use LWP::UserAgent qw( );

That's the same as

BEGIN {
    require LWP::UserAgent;
}

That way, I'm guaranteed not to import anything I don't want, and I use the familiar use I use for other modules.

Upvotes: 3

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