in reply to Ahh the map function

       map BLOCK LIST
       map EXPR,LIST
               Evaluates the BLOCK or EXPR for each element of
               LIST (locally setting "$_" to each element) and
               returns the list value composed of the results of
               each such evaluation.  In scalar context, returns
               the total number of elements so generated.  Evalu­
               ates BLOCK or EXPR in list context, so each ele­
               ment of LIST may produce zero, one, or more ele­
               ments in the returned value.

                   @chars = map(chr, @nums);

               translates a list of numbers to the corresponding
               characters.  And

                   %hash = map { getkey($_) => $_ } @array;

               is just a funny way to write

                   %hash = ();
                   foreach $_ (@array) {
                       $hash{getkey($_)} = $_;
                   }

[download]

So, for each element in @edittypes (let's say $_ = 'foo'), it would spit out \.foo. The return value from map would be a list of these transformed elements.

Update: Corrected escaping of backslash.


_______________
D a m n D i r t y A p e
Home Node | Email

Replies are listed 'Best First'.
Re: Re: Ahh the map function
by Anonymous Monk on Jul 07, 2002 at 04:16 UTC 
     
$regex = join('|', map{"\\.$_" }@edittypes);
 inerror("You can only edit \"@edittypes\"") unless /$regex/i;

    [download]
    Im confused with whole thing can oyu explain in words how it does it.
[reply]
[d/l]

      OK, Let's say @edittypes = ( 'foo', 'bar', 'zoot' ). For each of these, map sets $_ to the array element, and spits out the return value of the block. So, map returns ( '\.foo', '\.bar', '\.zoot' ). These are joined with pipes; after executing the first line, you have $regex = '\.foo|\.bar|\.zoot'.

      Now, since you don't appear to be matching to anything in the second line, I am guessing this came from inside a loop with an implicit value. Whatever $_ is equal to when the second line runs is matched against $regex, case insensitive. If there's no match, call the inerror function, whatever that may be.

      Does that clear it up?

      Update: Corrected escaping of backslash.


      _______________
      D a m n D i r t y A p e
      Home Node | Email
[reply]
[d/l]
[select]
      A reply falls below the community's threshold of quality. You may see it by logging in.
      A reply falls below the community's threshold of quality. You may see it by logging in.

In Section Seekers of Perl Wisdom