.WHAT gives you the actual type, whereas .^name gives you a string
that is the name.
In Perl6 types are things you can pass around; which is good because
you can have more than one with the same name.
sub bar (){
my class Foo { }
}
sub baz (){
my class Foo { }
}
my $a = bar().new();
bar() === $a.^name; # False (one is a Foo type object, the other a string)
bar() === $a.WHAT; # True (both are the Foo type object)
bar().^name === baz().^name; # True (but they are different types)
bar().WHAT === baz().WHAT; # False (both are type objects, but
they are different types)
"".WHAT =:= Str; # True (both are the Str type object)
Basically think about .WHAT as being the Perl6 equivalent of `typeof()`.
On Mon, Oct 29, 2018 at 12:12 PM Joseph Brenner <[email protected]> wrote:
>
> Brandon Allbery <[email protected]> wrote:
> > Two issues:
> >
> > (1) all standard exceptions are in or under the X:: namespace.
> >
> > (2) .WHAT doesn't show names with their namespaces, whereas .^name does.
> >
> > pyanfar Z$ 6 'my $r = 4/0; say $r; CATCH {default {say .^name}}'
> > X::Numeric::DivideByZero
>
> Thanks. I didn't get that the behavior of WHAT and ^name were that different.
>
>
>
> > On Mon, Oct 29, 2018 at 1:04 PM Joseph Brenner <[email protected]> wrote:
> >
> >> I was just looking into doing some finer-grained exception handling,
> >> so I tried this:
> >>
> >> use v6;
> >> try {
> >> my $result = 4/0;
> >> say "result: $result";
> >> CATCH {
> >> # when DivideByZero { say "Oh, you know."; }
> >> default { say .WHAT; .Str.say } # (DivideByZero) Attempt
> >> to divide 4 by zero using div
> >> }
> >> }
> >>
> >> The first time through, The .WHAT tells me I've got
> >> "DivideByZero", and so I added the line that's commented out
> >> here, at which point I got the error:
> >>
> >> ===SORRY!===
> >> Function 'DivideByZero' needs parens to avoid gobbling block (or
> >> perhaps it's a class that's not declared or available in this scope?)
> >>
> >> Putting parens around (DivideByZero) doesn't help:
> >>
> >> Undeclared name:
> >> DivideByZero used at line 12
> >>
> >> My impression was this would just work from looking
> >> at the examples using things like X::AdHoc here:
> >>
> >> https://docs.perl6.org/language/exceptions
> >>
> >
> >
> > --
> > brandon s allbery kf8nh
> > [email protected]
> >
