# from Dr.Ruud
# on Sunday 21 January 2007 05:30 am:
>> I also need to get Perl v53.46.48 installed, but that
>> should be a piece of cake.
>
>$ perl -wle 'print v53.46.48'
>5.0
Heh, that was just a joke about how the overridden require sees version
numbers. Actually, it seems to be something to do with upgrading the
value to a string if you use it as one. The 53.46.48 stuff appears to
have come from ord("5") . ord(".") . ord("0"). I suppose the compiler
has tagged it as a version before it comes into require?
BTW, for those that haven't seen this before, the vstring v8.9.10 is a
three byte string: chr(8) . chr(9) . chr(10).
----------
#!/usr/bin/perl
use warnings;
use strict;
BEGIN {
*CORE::GLOBAL::require = sub {
my ($module) = @_;
warn "wants $module";
CORE::require $module;
};
}
require 5.0004 ;
print "ok\n";
---------
$ perl overriding_require.1.pl
wants 5.0004 at overriding_require.1.pl line 9.
Perl v53.46.48 required--this is only v5.8.4, stopped at
overriding_require.1.pl line 10.
Now, if I don't use the $module value for anything before passing it
along, I guess I get to delete a bunch of the special cases from
Devel::TraceDeps:
my ($module) = @_;
my $thing = $module;
warn "wants $thing";
CORE::require $module;
...
require 5.0004 ;
require 5.0;
require 5.006;
require v5.0.4;
require 5.0.4;
print "ok\n";
$ perl overriding_require.2.pl
wants 5.0004 at overriding_require.2.pl line 10.
wants 5 at overriding_require.2.pl line 10.
wants 5.006 at overriding_require.2.pl line 10.
wants at overriding_require.2.pl line 10.
wants at overriding_require.2.pl line 10.
ok
Neat, huh? I suppose I could add "who says they need what version" to
the output, eh?
--Eric
--
Turns out the optimal technique is to put it in reverse and gun it.
--Steven Squyres (on challenges in interplanetary robot navigation)
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