Re^2: Interesting behavior in eval block

in reply to Re: Interesting behavior in eval block
in thread Interesting behavior in eval block

That makes sense, but this is a contrived minimal example of the implementation. This will be run well after compile time off of config data, or object instantiation values. So the questions is can I somehow muck with the symbol table to get where I want to be? Maybe something like

   while ( my($module, $args) = each %$toLoad ) {
      my $str = "use $module "; # to fix typo in example
      $str   .= 'qw(' . $args . ')' if $args ne '1';
      eval $str;

      # Try and remap symbol tables to the right spot
      unless ( $args eq '1' ) {
         no strict 'refs';
         foreach my $key ( split/\s+/, $args ) {
            *$key = *$module::$key;
         }
      } # END unless args eq 1  
   } # END while each toLoad
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This would cover the standard cases but fail for things like use CGI qw(:all); and similar megaKeywords

I imagine this is a standard pattern, I just don't know where to look for the docs to get at what I want without potentially digging into other modules EXPORT_* variables, which doesn't seem right either

use perl;
Everyone should spend some time pounding nails with their forehead for a while before they graduate to complicated stuff like hammers. - Dominus

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Re^3: Interesting behavior in eval block by ikegami (Patriarch) on Jun 19, 2008 at 18:52 UTC
Your "trick" doesn't work. You're just duplicating the work the implicit `import` in `use` already does. Like I said in my original post, it's when it happens that's important. You have the right idea, but it needs to be done at compile-time. Fortunately, it's very simple since Perl already provides a means of declaring a function that's to be defined at a later time. `sub gettimeofday(); # Eventually. eval "use Time::HiRes qw( gettimeofday ); 1" or die "Unable to load Time::HiRes: $@\n"; print(gettimeofday);` [download] The parens in "`sub gettimeofday();`" are only there because Time::HiRes declares the function using that prototype.	[reply] [d/l] [select]

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Re^3: Interesting behavior in eval block
by ikegami (Patriarch) on Jun 19, 2008 at 18:52 UTC

Your "trick" doesn't work. You're just duplicating the work the implicit import in use already does. Like I said in my original post, it's *when* it happens that's important.

You have the right idea, but it needs to be done at compile-time. Fortunately, it's very simple since Perl already provides a means of declaring a function that's to be defined at a later time.

sub gettimeofday();

# Eventually.
eval "use Time::HiRes qw( gettimeofday ); 1"
   or die "Unable to load Time::HiRes: $@\n";

print(gettimeofday);
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The parens in "sub gettimeofday();" are only there because Time::HiRes declares the function using that prototype.

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