in reply to Side effects of use-ing base (vs our @ISA)

Are you sure you need the 'use lib' in the "second thing"? For me it works with just the 'use Totally::Fake', without the need of 'use lib'.

Also note that "-M Foo" is *not* the same as "use Foo;". Perlrun says: 

       -M[-]module
       -M[-]'module ...'
       -[mM][-]module=arg[,arg]...
            -mmodule executes "use" module "();" before executing
            your program.

            -Mmodule executes "use" module ";" before executing
            your program.  You can use quotes to add extra code
            after the module name, e.g., '-Mmodule qw(foo bar)'.

            If the first character after the -M or -m is a dash
            ("-") then the 'use' is replaced with 'no'.

            A little builtin syntactic sugar means you can also
            say -mmodule=foo,bar or -Mmodule=foo,bar as a short-
            cut for '-Mmodule qw(foo bar)'.  This avoids the need
            to use quotes when importing symbols.  The actual
            code generated by -Mmodule=foo,bar is "use module
            split(/,/,q{foo,bar})".  Note that the "=" form
            removes the distinction between -m and -M.

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The important part is: 

-mmodule executes "use" module "();"

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Note the trailing (), meaning that the modules import routine will not be called. So, Exporter won't export the variables.

Abigail

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Re: Re: Side effects of use-ing base (vs our @ISA)
by ViceRaid (Chaplain) on Sep 10, 2003 at 11:29 UTC

    Thanks Abigail

    Are you sure you need the 'use lib' in the "second thing"? For me it works with just the 'use Totally::Fake', without the need of 'use lib'.

    I've double-checked it and stripped it down to it's barest bones:

    ### Totally/Fake.pm
use strict;

package Totally::Fake;
our @ISA = qw(Exporter);
our ($fake, $faker);
our @EXPORT = qw($fake $faker);

### my_script.pl
use strict;

# uncomment this to make it work
# use lib '/long/path/to/nowhere';

use Totally::Fake;
print $fake;

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    ... and I'm still getting the odd behaviour (perl 5.8.0).

    Also note that "-M Foo" is *not* the same as "use Foo;" ... -Mmodule executes "use" module ";" before executing your program. (perldoc perlrun)

    Doesn't this mean -MFoo == use Foo; but -mFoo != use Foo;? In that -M will call the import routine for the default set of symbols, but -m will not call it.

    Cheers
    ViceRaid

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[d/l]
      Your Totally/Fake.pm doesn't have a "use Exporter;". How adding 'use lib' makes perl compile my_script.pl seems like a bug to me.

      Doesn't this mean -MFoo == use Foo; but -mFoo != use Foo;? In that -M will call the import routine for the default set of symbols, but -m will not call it.

      Yes it does. I completely misread.

      Abigail

[reply]
        Ah, I got it.

        "use lib" does a "use Config", which does a "use Exporter". So, if you have a "use lib", Exporter is loaded, making your Totally::Fake.pm work, despite the absense of "use Exporter" in that file.

        Abigail

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