Re: Using pos() inside given/when

Kenosis and educated_foo have answered the question. I just want to add a few comments:

On my version of perl (v5.16.0) the code in the OP produces an infinite loop.
The real code is, no doubt, more complex than the code in the example. But I suspect that, even so, the logic could be significantly clarified by rearranging the loops. Certainly, the example as given can be written with just one loop:
```
print pos $h->{s}, "\n" while $h->{s} =~ /a/g;
[download]
```
The line:
```
$h->{s} =~ m/^/g;
[download]
```
is presumably there only to reset pos, in which case I suggest the following would be clearer:
```
pos($h->{s}) = undef;
[download]
```

Hope that helps,

Comment on Re: Using pos() inside given/when Select or Download Code

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Re^2: Using pos() inside given/when by Anonymous Monk on May 10, 2013 at 10:51 UTC
Thanks for your answers. Switching to a `for` solved that problem (I could not have rewritten it with a simple loop, as I have a lot of `when` in a Lex-like code). If I understand correctly the fact that in v5.16 the same code gives an infinite loop, it's that the given's version of $_ have been "fixed", in the sense that a new scalar is now created for each iteration (hence the pos() function and the matching are in accord). But the same thing with the for loop will still work as I expect ? If the when construct does not care from where does the $_ variable comes from, do you know what was the need to introduce given rather than just stick with for ? Anyway, thanks for your help!	[reply] [d/l] [select]
Re^3: Using pos() inside given/when by tobyink (Canon) on May 10, 2013 at 11:30 UTC
`for` and `given` both use `$_`. The difference is that `for` uses `our $_` and aliases it to the item, while `given` copies (though I believe it's a cheap optimized copy) the item to `my $_`. `package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name`	[reply] [d/l] [select]