Strange given/when deparsing

KSURi has asked for the wisdom of the Perl Monks concerning the following question:

Hello, monks!

There is a simple script:

use Modern::Perl;

my $x = 2.3;
given($x) {
    when(int) { say 'match' } # int($_) ~~ $x
    default { say 'no match' }
}
[download]

It prints 'no match' as expected.

There is also another script with a little difference:

use Modern::Perl;

my $x = 2.3;
given($x) {
    when($_) { say 'match' } # $_ ~~ $x
    default { say 'no match' }
}
[download]

Prints 'match' as expected.

The strangeness is that B::Deparse produces the same output for both scripts:

use Modern::Perl;
use warnings;
use strict 'refs';
BEGIN {
    $^H{'feature_say'} = q(1);
    $^H{'feature_state'} = q(1);
    $^H{'feature_switch'} = q(1);
}
my $x = 2.3;
given ($x) {
    when ($_) {
        say 'match';
    }
    default {
        say 'no match';
    }
}
[download]

Why is this so? Is this a bug of B::Deparse?

Comment on Strange given/when deparsing Select or Download Code

Replies are listed 'Best First'.
Re: Strange given/when deparsing by ikegami (Patriarch) on Jun 09, 2009 at 15:53 UTC
Is this a bug of B::Deparse? Yes, although it might have already been fixed in forthcoming 5.10.1. You can see the difference with the more precise (but verbose) B::Concise: `g <2> smartmatch sK/2 ->h d <0> padsv[$_:46,51] s ->e f <1> int[t4] sK/1 ->g e <0> padsv[$_:46,51] s ->f` [download] `f <2> smartmatch sK/2 ->g d <0> padsv[$_:46,51] s ->e e <0> padsv[$_:46,51] s ->f` [download] `when(int) { say 'match' } # int($_) ~~ $x` You have the order backwards. It's `$x ~~ int($_)`. (Well, `$_ ~~ int($_)` really.)	[reply] [d/l] [select]
Re^2: Strange given/when deparsing by akho (Hermit) on Jun 09, 2009 at 16:03 UTC
Isn't `~~` commutative?	[reply] [d/l]
Re^3: Strange given/when deparsing by ikegami (Patriarch) on Jun 09, 2009 at 16:12 UTC
It might have been. It might be. It won't be. Update: Is the following clearer? It might have been commutative in the past. It might be commutative now. It won't be commutative in the future.	[reply]
Re^4: Strange given/when deparsing by akho (Hermit) on Jun 09, 2009 at 16:41 UTC
Re^5: Strange given/when deparsing by ikegami (Patriarch) on Jun 09, 2009 at 16:46 UTC
Some notes below your chosen depth have not been shown here
Re: Strange when/given deparsing by akho (Hermit) on Jun 09, 2009 at 11:06 UTC
Very probably. Only `perl` can parse Perl, after all; and `given/when` is quite new.	[reply] [d/l] [select]


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