in reply to Re^2: map()'s BLOCK and deviations from othogonality...
in thread map()'s BLOCK and deviations from othogonality...

This is even documented in perlref: 
           Because curly brackets (braces) are used for several other 
+things
           including BLOCKs, you may occasionally have to disambiguate
+ braces
           at the beginning of a statement by putting a "+" or a "retu
+rn" in
           front so that Perl realizes the opening brace isn't startin
+g a
           BLOCK.  The economy and mnemonic value of using curlies is 
+deemed
           worth this occasional extra hassle.

           For example, if you wanted a function to make a new hash an
+d return
           a reference to it, you have these options:

               sub hashem {        { @_ } }   # silently wrong
               sub hashem {       +{ @_ } }   # ok
               sub hashem { return { @_ } }   # ok

           On the other hand, if you want the other meaning, you can d
+o this:

               sub showem {        { @_ } }   # ambiguous (currently o
+k, but may change)
               sub showem {       {; @_ } }   # ok
               sub showem { { return @_ } }   # ok

           The leading "+{" and "{;" always serve to disambiguate the 
+expres-
           sion to mean either the HASH reference, or the BLOCK.

[download]

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Replies are listed 'Best First'.
Re^4: map()'s BLOCK and deviations from othogonality...
by blazar (Canon) on Feb 25, 2005 at 09:37 UTC
    This is even documented in perlref:
    You're right! (What else?!?)

    I'm also ashamed, since I had read that section sometimes... OTOH retrospectively I'm slightly surprised that at least a few experienced perl hackers from clpmisc didn't recognize it at a first glance either... 

    Because curly brackets (braces) are used for several other things
including BLOCKs, you may occasionally have to disambiguate braces
at the beginning of a statement by putting a "+" or a "return" in
front so that Perl realizes the opening brace isn't starting a
BLOCK.  The economy and mnemonic value of using curlies is deemed
worth this occasional extra hassle.

    [download]
    Hmmm, it seems that the docs concentrate on the somewhat opposite situation, i.e. that in which a hashref is mistaken for a block. 
    The leading "+{" and "{;" always serve to disambiguate the expres-
sion to mean either the HASH reference, or the BLOCK.

    [download]
    I must say that while I find "+{" aesthetically appealing, I can't say the same of "{;". But of course that's just me...
[reply]
[d/l]
[select]

In Section Meditations