Philip Potter <philip.g.pot...@gmail.com> writes:
> On 5 May 2010 14:36, Harry Putnam <rea...@newsguy.com> wrote:
>> "Uri Guttman" <u...@stemsystems.com> writes:
>>
>>> HP> The output from the script below:
>>> HP> Shows 6 elements arrive in dispt($g, @ar) as @_. But when sub N(@_)
>>> HP> is called, no variables arrive there. @_ is empty. When it seems like
>>> HP> 5 elements should have arrived there
>>>
>>> well, it helps if you actually pass in arguments. @_ is NOT a global.FF
>>>
>>> HP> my $code = $dispt{$selection} || $dispt{'error'} ;
>>> HP> $code->();
>>>
>>> you aren't passing anything in to $code. you need to put something in
>>> the () which then is set in the @_ of the called sub.
>>
>> As usual, I'm a little confused here. First, what is a `global.FF'?
>
> I don't see "FF" in uri's original post, your reader may have mangled
> it. He said "@_ is NOT a global."
First. I see `FF' in your response above too. At the line beginning:
>>> well,
But you're right... its NOT in the original... odd.
Anyway, I understood he was saying NOT global.
What I asked is why that would matter. That is, the values or
elements in @_ arrive inside the `sub dispt {...}', so should be
available to anything inside `sub dispt {...}' right?
And `%hash = (...)' is inside `sub dispt {. %hash = (...)..}'
I do get confused often about how scope works.
Trying to subtract as much as I can and still see what is confusing to me.
In this little piece of code... I'm still missing why @_ has lost
its meaning in the spots indicated by comments below:
Not seeing why it matters that @_ is NOT global since we are only
looking for a value inside dispt {...} and the content is shipped in
with the call `dispt($val1,$val2)'
#!/usr/bin/perl
my $val1 = 'I am a value';
my $val2 = 'I am a second value';
dispt($val1,$val2)
sub dispt {
# HERE @_ is known
%hash = (
N => sub { print N(@_ # HERE it is not known) . "\n"; },
[...]
);
[...]
chomp(my $selection = <STDIN>);
my $code = $hash{$selection} || $hash{'error'} ;
$code->(); ## I realize this is what calls sub N() and passes
## any info, but what about the call to N(@_) above?
}
sub N {
# HERE no values for @_ are present.
[...]
}
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