Re (tilly) 3: Setting Globals in a Base Class

I have found the export_to_level function in Exporter to be unmaintained and unreliable. Its error handling in particular leaves something to be desired due to poor maintainance and bad misunderstandings about the internals of Carp that it is messing around with.

I would therefore recommend using:

goto &Exporter::import;
[download]

rather than using export_to_level. Yeah, it is a hack. But it is a hack that works reliably.

Comment on Re (tilly) 3: Setting Globals in a Base Class Download Code

Replies are listed 'Best First'.
(Ovid) Re: Re (tilly) 3: Setting Globals in a Base Class by Ovid (Cardinal) on Nov 07, 2001 at 20:54 UTC
Interestingly, that's the solution I came up with last night. `sub import { # two loops because we don't want to splice @_ while looping over +it if ( grep { /:(?:bar\|baz)/ } @_ ) { my $sub = caller(0) . '::set'; { no strict 'refs'; *{$sub} = \&set; } } # using goto to avoid updating caller goto &Foo::import; }` [download] I wound up providing a `&set` function for the globals, but needed to make it available as both a method and a function. When a person calls my constructor, they get the new method. If they want to use the methods as functions, I install the method in their namespace and then use goto to call the `&import` method of the base class. For those who don't understand that last bit, goto with a sub after it replaces the current subroutine called with the subroutine that you're calling. This has the effect of not updating the call stack, thereby allowing the base class to export to the client, instead of my class. Cheers, Ovid Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.	[reply] [d/l]

Replies are listed 'Best First'.

(Ovid) Re: Re (tilly) 3: Setting Globals in a Base Class
by Ovid (Cardinal) on Nov 07, 2001 at 20:54 UTC

Interestingly, that's the solution I came up with last night.

sub import {
    # two loops because we don't want to splice @_ while looping over 
+it
    if ( grep { /:(?:bar|baz)/ } @_ ) {
        my $sub = caller(0) . '::set';
        {
            no strict 'refs';
            *{$sub} = \&set;
        }
    }
    # using goto to avoid updating caller
    goto &Foo::import;
}
[download]

I wound up providing a &set function for the globals, but needed to make it available as both a method and a function. When a person calls my constructor, they get the new method. If they want to use the methods as functions, I install the method in their namespace and then use goto to call the &import method of the base class.

For those who don't understand that last bit, goto with a sub after it replaces the current subroutine called with the subroutine that you're calling. This has the effect of not updating the call stack, thereby allowing the base class to export to the client, instead of my class.

Cheers,
Ovid

Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.

[reply]
[d/l]