Sorry, just posted to Jeff only.
Thanks for the answer but what I want to know is the meaning of %$$self. I
understand autovivification ( data structures spring into existence ).
However, the part I don't understand is %$$self. Shouldn't it be %$self? (
By the definition, you can always put a reference in place of the literal
in the variable.
i.e. $self{k} and $$reftoself{k}. Replacing "self" with "$reftoself" is
equivalent.
---- Thanks
Atul
Jeff 'japhy/Marillion' Pinyan <[EMAIL PROTECTED]>
09/18/01 08:14 PM
Please respond to japhy
To: [EMAIL PROTECTED]
cc: [EMAIL PROTECTED]
Subject: Re: autovivification of typeglobs
On Sep 18, [EMAIL PROTECTED] said:
>open my $self, $from, @_ or croak "can't open $from@_:$!";
>" ... the my $self furnishes undefined scalar to open, which knows to
>autovivify it into a typeglob. .... " and further mentions autovivifying
a
When you use an undefined value as a reference, Perl creates that
reference for you automatically. THAT is autovivification. Thus, when
you do:
my $x;
$x->{foo} = 10;
$x->{bar}[5] = 20;
You've autovivified $x as a hash reference from the second line, and
autovivified $x->{bar} as an array reference on the third line.
When you do:
open my($foo), $path;
Perl is expecting a typeglob. If you give it an undefined value, it
autovivifies the typeglob reference, so *$foo is the filehandle. However,
references to filehandles are accepted wherever a filehandle is, so you
can just use $foo and get away with it.
--
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 **
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