On Oct 18, Curtis Poe said:
>> Friends -- Could you briefly explain the term "auto-vivification"? I have
>> seen this quite a few times in some of the responses.
>
>Auto-vivification is trying to access a hash entry that doesn't exit. If that is
>done, the hash
>entry is typically created with an 'undef' value.
Incorrect.
>my %hash = ( foo => 'bar', baz => 'qux' );
>
>print $hash{ 'foo' }; # prints 'bar'
>print $hash{ 'stuff' }; # prints nothing, but now $hash{ 'stuff' } exists and is
>equal to undef
No. Auto-vivification refers to the automatic generation of a reference
where there was originally undef (or nothing). It is not related (or at
least restricted) to hashes.
Here is an example:
%foo = ( this => [10,20,30], that => [40,50,60] );
print "@{[ %foo ]}\n"; # this ARRAY(...) that ARRAY(...)
print $foo{this}[1]; # 20
print $foo{that}[2]; # 60
print $foo{those}[3]; # nothing
print "@{[ %foo ]}\n"; # this ARRAY(...) that ARRAY(...) those ARRAY(...)
Notice how using $foo{those} as a reference caused it to become an array
reference (albeit an empty one)?
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
** Look for "Regular Expressions in Perl" published by Manning, in 2002 **
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
