Charles K. Clarkson <> wrote:
> Petr Vileta wrote:
>
>> I have public hash and in sub{}
>
> A public hash sounds like a really bad idea. Why not use a
> lexically scoped hash and specifically pass it into the sub?
>
>
>> Example with success but maybe is possible to write it better:
>>
>> our $hash;
>> $hash->{first} = 1;
>> $hash->{second} = 2;
>> &mysub;
>> print $hash->{second};
>>
>> sub mysub {
>> my $new_hash;
>> # make local copy
>> $new_hash->{$_} = $hash->{$_} foreach (keys %{$hash});
>> print $new_hash->{second};
>> $new_hash->{second} = 10;
>> print $new_hash->{second};
>> }
>
>
> my $hash = {
> first => 1,
> second => 2,
> };
>
> mysub( $hash );
>
> print $hash->{second};
>
> sub mysub {
> my %copy = %{ shift @_ };
>
> print $copy{second};
> $copy{second} = 10;
> print $copy{second};
> }
>
> __END__
>
This, and other suggestions, performs a shallow copy, which is fine for
the example given where the hash values are scalars. If, on the other
hand, the values were hashes containing arrays of objects that contained
arrays of hashes, for example, a shallow copy may not be good enough. A
deep copy is required that follows every reference and copies whatever
it refers to, which is a lot more complex. Luckily, however, the
Activestate distribution provides modules that can do this. See
Data::Dumper and Storable.
>
>> (My server reject all messages from Yahoo and Hotmail. Send me
>> your mail from another non-spammer site please.)
>
> Replace "reject" with "rejects"
Or perhaps "will reject".
HTH
--
Brian Raven
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