Let's Add Some Spice

Randal L. Schwartz merlyn at stonehenge.com
Tue Jun 6 12:09:10 CDT 2000

>>>>> "Aaron" == Aaron Jensen <atjensen at home.com> writes:

Aaron> 19 foreach(values %FIELDS){
Aaron> 20     grep(%ALL_FIELDS{$_}++, @$_);
Aaron> 21 }

If that's really line 20, Lincoln should be shot.  The proper syntax
is $ALL_FIELDS{$_}++.  Unfortunately, the current Perl compiler
doesn't catch this error.

Aaron> My question is, what is happening on lines 19 - 21?  I've
Aaron> stared at it and stared at it, looked in Perl books,
Aaron> experimented, and have a very fuzzy approximation/guess of
Aaron> what is going on.  I know what the result is, just not how
Aaron> that result is acheived.  How can clear things up for me?

if $FIELDS{fred}[3] = "betty", then $ALL_FIELDS{"betty"} is set to true,
for any betty, fred, or 3. :)  Walk through the dereferencing for
the details.  I'd've written this as:

for (values %FIELDS) {
  for (@$_) {
    $ALL_FIELDS{$_} = 1;

Does that make more sense now?

Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn at stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
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