Just a Theory

By David E. Wheeler

Posts about Hacks

How Does DateTime Ignore CORE::GLOBAL::time?

For the life of me, I can’t figure out why this test fails. time returns my overridden time, and DateTime just calls scalar time, so I would expect it to work. But DateTime appears to be somehow getting the time for CORE::time, instead.

#!/usr/bin/perl -w

use strict;
use DateTime;
use Test::More tests => 1;

BEGIN {
    *CORE::GLOBAL::time = sub () { CORE::time() };
}

my $epoch = time;
sleep 1;
try();

sub try {
    no warnings qw(redefine);
    local *CORE::GLOBAL::time = sub () { $epoch };
    is( DateTime->now->epoch, time );
}

Anyone got any bright ideas? This is a reasonably well-known technique, so I’m sure that I must be overlooking something obvious.

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