为什么不是“|"被超载了吗? [英] Why isn't '|' being overloaded?

问题描述

以下代码未按预期工作.我错过了什么?

The following code does not work as expected. What am I missing?

use strict;
use warnings;
use overload '|' => sub { 1 / ( 1 / $_[0] + 1 / $_[1] ) };

print( 5 | 5 ); # Prints '5' instead of '2.5'

推荐答案

overload 仅适用于受祝福的引用(对象").

overload works only on blessed references ("objects").

package MyNumber;
use strict;
use warnings;
use overload '|' => sub { 1 / ( 1 / +$_[0] + 1 / +$_[1] ) },
            '0+' => sub { $_[0]->{value} }, # Cast to number
            fallback => 1;                  # Allow fallback conversions

# "Constructor", bless number as MyNumber
sub num {
    my $self = { value => $_[0] };  # can be any reference
    return bless $self, "MyNumber";
}

print(num(5) | num(5));


my $a = num(5);
print ($a | 5); # This works too

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