Groups | Search | Server Info | Login | Register

Groups > comp.lang.perl.misc > #4798

Re: Embedding code in qq{}?

Show all headers | View raw

>>>>> "TM" == Tim McDaniel <tmcd@panix.com> writes:

  TM> In article <1fjg39-qnv2.ln1@anubis.morrow.me.uk>,
  TM> Ben Morrow  <ben@morrow.me.uk> wrote:
  >> 
  >> Quoth tmcd@panix.com:
  >>> In article <87limyk471.fsf@Gmail.com>, XeCycle  <XeCycle@Gmail.com>
  >>> wrote:
  >>> >Is it possible to use something like "${1+2}" -> "3"?
  >>> 
  >>> You made it clear in the rest of the article (which I trimmed) that
  >>> you were thinking about the right-hand side of a s///.  It turns out
  >>> that, in string contexts in general, you can do it.
  >>> 
  >>> Short answer:
  >>> ${\(1+2)}
  >> 
  >> If you must do this, then @{[...]} is clearer, since in both cases
  >> the internal code is evaluated in list context.

  TM> Both are in a scalar context, I think.

i know that to be wrong. one classic issue was that ${\bar()} always
calls in list context. there is no implicit way to get scalar context
there.
>>>>> "TM" == Tim McDaniel <tmcd@panix.com> writes:

  TM> In article <1fjg39-qnv2.ln1@anubis.morrow.me.uk>,
  TM> Ben Morrow  <ben@morrow.me.uk> wrote:
  >> 
  >> Quoth tmcd@panix.com:
  >>> In article <87limyk471.fsf@Gmail.com>, XeCycle  <XeCycle@Gmail.com>
  >>> wrote:
  >>> >Is it possible to use something like "${1+2}" -> "3"?
  >>> 
  >>> You made it clear in the rest of the article (which I trimmed) that
  >>> you were thinking about the right-hand side of a s///.  It turns out
  >>> that, in string contexts in general, you can do it.
  >>> 
  >>> Short answer:
  >>> ${\(1+2)}
  >> 
  >> If you must do this, then @{[...]} is clearer, since in both cases
  >> the internal code is evaluated in list context.

  TM> Both are in a scalar context, I think.

  TM> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

  TM> #! /usr/bin/perl
  TM> use strict;
  TM> use warnings;

  TM> sub tester {
  TM>     if (wantarray) {
  TM>         print "array context\n";
  TM>         return [ 11, 12, 13 ];
  TM>     } else {
  TM>         print "scalar context\n";
  TM>         return \(22);
  TM>     }
  TM> }

  TM> print "scalar: ", ${tester()}, "\n";
  TM> print "array: ", @{tester()}, "\n";

those are not correct tests. neither is being interpolated into a string
nor is \ being used. just a dereference in code will of course provide a
scalar context as you need a single scalar value to dereference.

change the code to "scalar: ${\tester()}\n" and "array: ${[tester()]}\n"
and see what happens. that is looking at the context in interpolation.

uri

Back to comp.lang.perl.misc | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Embedding code in qq{}? XeCycle <XeCycle@Gmail.com> - 2012-03-18 10:56 +0800
  Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-17 23:04 -0400
    Re: Embedding code in qq{}? XeCycle <XeCycle@Gmail.com> - 2012-03-18 12:14 +0800
  Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-18 07:07 +0000
    Re: Embedding code in qq{}? Ben Morrow <ben@morrow.me.uk> - 2012-03-18 08:37 +0000
      Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-18 22:28 +0000
        Re: Embedding code in qq{}? merlyn@stonehenge.com (Randal L. Schwartz) - 2012-03-18 16:18 -0700
          Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-19 02:21 +0000
            Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-19 00:14 -0400
              Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-19 06:42 +0000
                Re: Embedding code in qq{}? Ben Morrow <ben@morrow.me.uk> - 2012-03-19 16:40 +0000
        Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-18 19:29 -0400
    Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-18 15:24 -0400
      Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-18 22:33 +0000
        Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-18 19:24 -0400
          Re: Embedding code in qq{}? Ben Morrow <ben@morrow.me.uk> - 2012-03-19 00:49 +0000
            Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-18 22:05 -0400
          Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-19 02:55 +0000
            Re: Embedding code in qq{}? Uri Guttman <uri@stemsystems.com> - 2012-03-19 00:12 -0400
              Re: Embedding code in qq{}? tmcd@panix.com (Tim McDaniel) - 2012-03-19 07:00 +0000
                Re: Embedding code in qq{}? Ben Morrow <ben@morrow.me.uk> - 2012-03-19 16:43 +0000

csiph-web