Perl use vs. require
February 09, 2011 13:27:51 Last update: February 09, 2011 13:27:51
By the perldoc,
is exactly equivalent to:
Because of the
Also, file extension is required if
use Module LIST;
is exactly equivalent to:
BEGIN { require Module; Module->import( LIST); }
Because of the
BEGIN block, use is executed immediately. Therefore, it is not suitable for lazy loading of modules at runtime.
use does not work with a runtime variable:
C:\>perl $cgi = "CGI"; require $cgi; print $CGI::VERSION; ^Z Can't locate CGI in @INC (@INC contains: C:/Perl5.8/site/lib C:/Perl5.8/lib .) at - line 2.
require works:
C:\>perl
$cgi = 'CGI';
require "${cgi}.pm";
print $CGI::VERSION;
^Z
3.48
Also, file extension is required if
require is not passed a bareword:
// this works require CGI; // so does this require "CGI.pm"; // but NOT this require "CGI";
