Hi

I just realized that it's not possible to have independent each iterators for the same hash.

Is there any "lazy" alternative? I.e. w/o copying all keys in advance into an array?

Arrays are easier since the "keys" can be walked by incrementation like in c-style for-loop.

For illustration

  DB<140>  sub gen {
             my $href=shift;
             return sub { join " => ", each %$href }
           }

  DB<141> $iter1 =gen \%h; $iter2 =gen \%h

  DB<142> @h{a..d}=1..4
 => (1, 2, 3, 4)

  DB<143> print &$iter1,"\t" for 1..3
a => 1  d => 4  c => 3    

  DB<144> print &$iter2,"\t" for 1..3
b => 2          a => 1    

  DB<145> print &$iter1,"\t" for 1..3
d => 4  c => 3  b => 2    

  DB<146> print &$iter2,"\t" for 1..3
        a => 1  d => 4

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It seems impossible to have independent iterators, and copying the keys in advance isn't really efficient...

I already tried aliasing and referencing the hash, w/o effect it's always the same iterator...

UPDATE

Furthermore, this can cause really ugly bugs ...

Cheers Rolf

( addicted to the Perl Programming Language)

PS: 

lanx@nc10-ubuntu:~/perl$ perl -version

This is perl, v5.10.0 built for i486-linux-gnu-thread-multi

[download]

In reply to Indepedent lazy iterators for the same hash? by LanX

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