in reply to Re^3: writing a pragma
in thread writing a pragma

is there a way to write a module to work like strict. so that does something at compile time?

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Re^5: writing a pragma
by salva (Canon) on Apr 26, 2014 at 06:30 UTC
    In Perl it is easy to do things at compile time. You have BEGIN for that.

    A different mater is changing how the program is compiled. perl provides some hooks for doing it, but AFAIK, it must be done at the C level and requires a pretty good knowledge of the internals. See perlguts.

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Re^5: writing a pragma
by tobyink (Canon) on Apr 26, 2014 at 07:18 UTC

    That really depends on exactly what you want to do at compile time, doesn't it? Some things are easier than others.

    use Moops; class Cow :rw { has name => (default => 'Ermintrude') }; say Cow->new->name
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      I want to write a pragma, which reads the contents of file where it is imported.

      1. use mypragma;

      2. use Data::Dumper;

      3. my $hash = {1,2,3,4,5,6}

      4. print Dumper $hash;

      I want to get the lines from 2,3,4 into the mypragma which was loaded into memory for this program.

      I am not sure that this is possible, I just want to try.

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        sure its possible, but such a thing shouldn't be a pragma :) see caller and open and import and splice and zentara package/module tutorial.... 

        use NotAPragma;
...

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        NotAPragma.pm 

        package NotAPragma;
sub import {
   my ($package, $filename, $line) = caller;
   open my($infh), '<:raw', $filename
      or die "Can't open caller $filename : $!";
   my @lines = ( 'pad', readline $infh );
   close $infh;
   splice @lines, 0, $line;
   print "@lines\n"; ## << this is the ... after use NotAPragma;
}
1;

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