use Perl

• The pumpking advice (Score:2)

  by rafael (2125)

  Don't put a conditional into an assignment operator. What would be the return value of =? ? What would "$x = $y =? $z" do ?
  • Re: (Score:1)

    by dami (6728)

    > What would be the return value of =? ?
    
    Just what I wrote in original post : ($x =? expr) would mean
    ($tmp = expr and $x = $tmp)
    
    > What would "$x = $y =? $z" do ?
    $x = ($tmp = $z and $y = $tmp)
    
    so if $z is false, $y is untouched and $x is false, whereas with
    
    "$x =? $y =? $z"
    
    both $x and $y stay untouched if $z is false
• Easily done already. (Score:1)

  by Aristotle (5147)

  1. eval { $some_hash{some_key} = ( expr or die ) };

  2. $_ = expr or $_ for $some_hash{some_key};
  • Re: (Score:1)

    by dami (6728)

    > eval { $some_hash{some_key} = ( expr or die ) };
    this would catch exceptions raised in expr .

    > $_ = expr or $_ for $some_hash{some_key};
    well, not many readers would quickly guess that we are assigning something in the hash here
    • Re: (Score:1)

      by Aristotle (5147)

      My suggestions were actually tongue-in-cheek, particularly the eval-based one. I would never write code like that.

      But it occurs to me that you can just as well arrange the aliasing in #2 the other way around:

      $_ and $foo{bar} = $_ for $baz;

      Unlike my previous suggestion this also avoids the unnecessary assignment in case the expression is false. I might actually use this in real code, although I would probably not write it with if and a for construct rather than the for modifier.

      for ( expr ) { $foo{ba
• Luckily... (Score:1)

  by educated_foo (3106)

  Luckily perl has pass-by-reference that plays well with autovivification:

  sub update { $_[0] = $_[1] if $_[1]; $_[1] }