Re^3: adding items, but with interim results


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Re^3: adding items, but with interim results

by LanX (Saint)

on Mar 31, 2013 at 00:24 UTC ( [id://1026310]=note: print w/replies, xml )

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in reply to Re^2: adding items, but with interim results
in thread adding items, but with interim results

> but it presents a stumbling block to which it is perhaps unwise to expose a novice

I second this!

Especially because state has some implementation issues besides needing to be activated with use feature.

a simple my $z outside the map has the same effect and is backwards compatible.

   DB<104> @x=1..4
 => (1, 2, 3, 4)

  DB<105> use feature state; my @y = map { state $z = 0; $z += $_ } @x
+;
 => (1, 3, 6, 10)

  DB<106> my $z; my @y = map { $z += $_ } @x;
 => (1, 3, 6, 10)
[download]

and if the scope of $z is of importance, use blocks to limit it.

  DB<107> my @y; { 
           my $z;
           @y =  map { $z += $_ } @x;
          }
 => (1, 3, 6, 10)

  DB<109> my @y = do { my $z; map { $z += $_ } @x }
 => (1, 3, 6, 10)
[download]

Cheers Rolf

( addicted to the Perl Programming Language)