Original suggestion (comments stripped):
> {
> my $savedData = 0;
>
> sub rememberData
> {
> $savedData = shift if @_; # update with new value if given
> return $savedData; # return current value
> }
> }
Curtis Poe <[EMAIL PROTECTED]> wrote:
> Actually, you really don't want to try to lexically scope a subroutine
> like that (because you can't -- well, there is a way, but it involves
> messing with symbol tables and that's usually not a good idea).
1) He doesn't try to lexicaly scope a subroutine, but a variable ...
so that it's only available inside the subroutine.
2) You can't LEXICALY scope a variable with ANY symbol table
tricks ... You can hide it pretty well, but it'll be LOCAL at best, not
LEXICAL.
> Your code can easily result in mysterious "Variable $foo will not stay
> shared" errors. Here's a sample program to show why this is bad
> practice (even though it looks good):
>
> #!/usr/bin/perl -w
> use strict;
>
> first( "Ovid" );
> second();
> first( "foo" );
>
> sub first {
> my $argument = shift;
> second();
>
> sub second {
> print "$argument\n";
> }
> }
>
> That will print "Ovid" three times and warn you that the variable
> $argument will not stay shared.
There is one IMPORTANT difference between your code and the
original sugestion.
In your code the variable in question is lexical to a subroutine,
while in the original it's lexical to a "top-level" block.
The important difference is that the block will only be evaluated
once ... so it will create the lexical variable only once AND that
instance of the variable will be remembered by the subroutine.
In your code ... each time you call the outer subroutine a new
instance of the $argument varible will be created, but the iner
subroutine will only remember the first one.
To sum this up :
NEVER define a NAMED subroutine within another subroutine or a
block that will be evaluated more than once (like a loop for
example) !
But ... the original proposal is ALL RIGHT !
Jenda
P.S.: If you want to share a variable between two functions do it
like this :
{
my $var;
sub fun1 { ... }
sub fun2 { ... }
}
NEVER like this :
sub fun1 {
my $var;
...
sub fun2 { ... }
}
=========== [EMAIL PROTECTED] == http://Jenda.Krynicky.cz ==========
There is a reason for living. There must be. I've seen it somewhere.
It's just that in the mess on my table ... and in my brain.
I can't find it.
--- me
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