Re: When does while set $

This is explained in perlop in relation to <>:

   
    Ordinarily you must assign the returned value to a vari
    able, but there is one situation where an automatic
    assignment happens.  If and only if the input symbol is
    the only thing inside the conditional of a `while' state
    ment (even if disguised as a `for(;;)' loop), the value is
    automatically assigned to the global variable $_.
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--
John.

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Re: When does while set $_ ? by crenz (Priest) on Aug 01, 2002 at 09:28 UTC
Thanks, John. I did read the man pages, but didn't find this one. I guess I just naturally assumed that the while statement should assign `$_`. Is there any (simple) way to assign the outer `$_` inside the `match()` function when in a `while`-loop? Or would that involve some major hacking?	[reply] [d/l] [select]
Re: Re: When does while set $_ ? by jmcnamara (Monsignor) on Aug 01, 2002 at 10:02 UTC
You could localise `$_` as follows: `while (local $_ = match('a')) { print "- $_\n"; }` [download] However, it would be better to use `grep()` instead of your match() function. Then all of your code could be replaced with the following line: `;-)` `print "- $_\n" for grep {/a/} @data;` -- John.	[reply] [d/l] [select]
Re: When does while set $_ ? by crenz (Priest) on Aug 01, 2002 at 10:34 UTC
Thanks. Unfortunately, using `grep()` is not an option -- the original `match()` could involve multiple `m//` or a SQL query, depending on the data interface selected ;-). But I wonder how four `grep()`'s compare to four `m//`'s in a foreach loop... I guess the latter approach still wins, because the array needs to be traversed only once.	[reply] [d/l] [select]