Why the change to read-only lists in 5.6.x?

I know it's been discussed before, I'm not a SuperSearch guru. *sighs*

foreach my $value (qw(a b c)) {
    $value .= '1';
    print "$value\n";
}
[download]

That works under 5.0.x, but not 5.6.x ... I personally like the change, but can't remember why it happened. (A coworker asked me, bitching about a script that now doesn't work.)

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Comment on Why the change to read-only lists in 5.6.x? Download Code

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Re: Why the change to read-only lists in 5.6.x? by japhy (Canon) on Sep 05, 2001 at 18:45 UTC
The change has occurred because `qw()` no longer becomes `split ' ', q()` at compile-time. The reason for that was because `qw()` in scalar context was splitting to `@_` and returning the number of elements (which is probably less than good). So now, `qw()` is turned into a physical list at compile-time. That means your code is: `foreach my $value (('a', 'b', 'c')) { $value .= '1'; print "$value\n"; }` [download] So you're trying to modify constants. Note, also, that now you can directly subscript a `qw()`, or use it in a `for` statement without surrounding parentheses: `$vowel = qw( a e i o u )[ rand 5 ]; for qw( a e i o u ) { # ... }` [download] Weird looking, eh? _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl hacker. `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l] [select]
Re: Why the change to read-only lists in 5.6.x? by trantor (Chaplain) on Sep 05, 2001 at 17:38 UTC
It seems to be coherent with the fact that a, b and c are constants, not lvalues, so you should not be allowed to modify their value. -- TMTOWTDI	[reply]