Joe Gottman wrote:
>
> I just read Exegesis 4, and I have a few questions about private
> variables. First, is it possible to have 2 private variables of the same
> name in different functions?
No. At least, not in different functions belonging to the same
namespace (i.e. module, class, or package)
> For instance, what would happen in the
> following code?
>
> sub func1() {
> our $varname is private \\= 1;
> return $varname;
> }
>
> sub func2() {
> our $varname is private \\= 2;
Fatal error: "Private variable $varname declared in two distinct scopes".
> Second, in the above code, the "\\=" operator is used to initialize the
> private variable. This allows it to be initialized the first time the
> function is called, but prevents it from being reinitialized subsequent
> times as long as the variable never becomes undefined. But what if the
> variable can become undefined? In that case, the next time you call the
> function the variable will be reinitialized, whether you want it to or not.
In which case, use an external declaration:
{
our $varname is private = 1;
sub func1() {
return $varname;
}
}
or just:
{
my $varname = 1;
sub func1() {
return $varname;
}
}
>
> Both of these show that "private" variables in Perl6 do not quite replace
> C or C++ static variables. It would be nice if there was some way to do
> something like this:
>
> my $foo is static = 3;
See above.
> so that $foo acts like a C++ static variable, i.e. its value always persists
> between calls to the function containing it, and the initialization code is
> performed only once. Unfortunately, I have no idea how this would be
> implemented in Perl 6.
Probably like this:
sub func1() {
my $varname is static = 1;
return $varname;
}
:-)
But I'm still to convince Larry of the rightness of providing that
extra Way To Do It.
Damian
