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

Monks,

why is 

for ( ; ; my @socks = $BASKET -> can_read(2) ) {
  ...
}

# different than:

while ($BASKET) {
  my @socks = $BASKET -> can_read(2);
  ...
}

[download]
other than the obvious conditional difference. i found that my IO::Select code was not working with the first example, but when I switched to the second example, it worked. Anyone have an idea as to what is causing this?

thanks,
brother dep.

--
transcending "coolness" is what makes us cool.

Replies are listed 'Best First'.
Re: for vs. while question
by MrNobo1024 (Hermit) on Mar 07, 2001 at 05:49 UTC
    in for(;;code), the code is executed at the end of the loop, not the beginning.
[reply]
Re: for vs. while question
by merlyn (Sage) on Mar 07, 2001 at 05:49 UTC
    Move your expression from third position to the first position: 
    for (my @socks = $BASKET -> can_read(2); ; ) { 
  ... 
}

    [download]
    In the place you put it, it's executed at the bottom of the loop, not the top.

    -- Randal L. Schwartz, Perl hacker

    update: No, read further down.
[reply]
[d/l]
      Won't that put it outside of the loop (so it's only executed once)?
[reply]
        Blimey yes. Ugh. OK, make it the conditional then: 
        for (;$BASKET and (my @socks = $BASKET -> can_read(2)) or 1); ) {  
  ...  
}

        [download]
        and now it's nearly like the original non-for code.

        Probably simpler just to use the while. {grin}

        -- Randal L. Schwartz, Perl hacker

[reply]
[d/l]

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