BEGIN {
  $module = somecond() ? "Text::CSV" : "Text::CSV_XS";

  require $module;
  $module->import;
}
[download]

_________
broquaint

require "Text::CSV" is much different than require Text::CSV. For your code to work, you'd need to s-::-/-g on $module for the require (but not for the import).

You can also use a lexical. Note that my declarations happen when the statement is compiled but my initializations happen when the statement is run. So:

use strict;

my $module;
BEGIN {
    $module= ... ? 'Text::CSV' : 'Text::CSV_XS';
    my $file= $module;
    $file =~ s-::-/-g;
    require "$file.pm";
    $module->import();
}

my $csv = $module->new();
[download]

Using eval "use $module" avoids this complication. Which to prefer is mostly a matter of taste (unless there is "risk" of $module ending up containing something strange).
                - tye

Actually, no, it's not a matter of taste. It's best to avoid eval STRING whenever possible since it forces dynamic runtime recompilation, and is thus rather slow. An eval BLOCK is always preferable. If you can represent the package names as literals (barewords) within your program, use this:

if (something()) {
    eval {
        require Text::CSV;
        Text::CSV->import;
    }
} else {
    eval {
        require Text::CSV_XS;
        Text::CSV_XS->import;
    }
}
[download]

The eval BLOCK syntax as well allows you to catch any fatal errors, storing them in $@:

die "Couldn't load module: $@" if ($@);
[download]

require "Text::CSV" is much different than require Text::CSV

Ah yes, of course. I've written code to do the appropriate munging of a bareword many times, don't know why I forgot it this time. Anyhow my code should really look like this

BEGIN {
  (my $file = ($module =
    somecond() ? "Text::CSV" : "Text::CSV_XS")".pm") =~ s{::}(/)g;

  require $file;
  $module->import;
}
[download]


HTH

_________
broquaint

Why use Text::CSV? It's slower and it's broken. If you have Text::CSV_XS, use it. It's faster and it's not broken. In any event, here's one way (untested):

my $CSV_CLASS = $boolean ? $module1 : $module2;
eval "use $CSV_CLASS";

if ($@) {
    croak "Could not use $CSV_CLASS: $@";
}

my $csv = $CSV_CLASS->new;
[download]

Cheers,
Ovid

Looking for work. Here's my resume. Will work for food (plus salary).
New address of my CGI Course.

package MyText;

sub init_XS {
    my $class = shift;
    my $usexs = shift;
    if ($usexs) {
        eval {
            use Text::CSV_XS;
            @ISA = ('Text::CSV_XS');
        }
    }
    else {
        eval {
            use Text::CSV;
            @ISA = ('Text::CSV');
        }
    }
}
1;
[download]

use MyText;

my $usexs = 1;     #decide whether to use XS

MyText->init_XS($usexs);

my $csvobj = MyText->new();   

#Text::CSV_XS->new gets called if $usexs is true.
#Text::CSV->new    gets called if $usexs is false.

#do stuff with $csvobj
[download]

--

flounder