Re: Exception Handling, DivideByZero
.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() === $a.WHAT; # True (both are the Foo type object)
bar().^name === baz().^name; # True (but they are different types)
bar().WHAT === baz().WHAT; # False (both are type objects, but
they are different types)
"".WHAT =:= Str; # True (both are the Str type object)
Basically think about .WHAT as being the Perl6 equivalent of `typeof()`.
On Mon, Oct 29, 2018 at 12:12 PM Joseph Brenner wrote:
>
> Brandon Allbery wrote:
> > Two issues:
> >
> > (1) all standard exceptions are in or under the X:: namespace.
> >
> > (2) .WHAT doesn't show names with their namespaces, whereas .^name does.
> >
> > pyanfar Z$ 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 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: $result";
> >>CATCH {
> >>#when DivideByZero { say "Oh, you know."; }
> >>default { say .WHAT; .Str.say } # (DivideByZero) Attempt
> >> to divide 4 by zero using div
> >>}
> >>}
> >>
> >> The first time through, The .WHAT tells me I've got
> >> "DivideByZero", and so I added the line that's commented out
> >> here, at which point I got the error:
> >>
> >>===SORRY!===
> >>Function 'DivideByZero' needs parens to avoid gobbling block (or
> >> perhaps it's a class that's not declared or available in this scope?)
> >>
> >> Putting parens around (DivideByZero) doesn't help:
> >>
> >>Undeclared name:
> >> DivideByZero used at line 12
> >>
> >> My impression was this would just work from looking
> >> at the examples using things like X::AdHoc here:
> >>
> >> https://docs.perl6.org/language/exceptions
> >>
> >
> >
> > --
> > brandon s allbery kf8nh
> > allber...@gmail.com
> >
Re: Exception Handling, DivideByZero
Brandon Allbery wrote:
> Two issues:
>
> (1) all standard exceptions are in or under the X:: namespace.
>
> (2) .WHAT doesn't show names with their namespaces, whereas .^name does.
>
> pyanfar Z$ 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 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: $result";
>>CATCH {
>>#when DivideByZero { say "Oh, you know."; }
>>default { say .WHAT; .Str.say } # (DivideByZero) Attempt
>> to divide 4 by zero using div
>>}
>>}
>>
>> The first time through, The .WHAT tells me I've got
>> "DivideByZero", and so I added the line that's commented out
>> here, at which point I got the error:
>>
>>===SORRY!===
>>Function 'DivideByZero' needs parens to avoid gobbling block (or
>> perhaps it's a class that's not declared or available in this scope?)
>>
>> Putting parens around (DivideByZero) doesn't help:
>>
>>Undeclared name:
>> DivideByZero used at line 12
>>
>> My impression was this would just work from looking
>> at the examples using things like X::AdHoc here:
>>
>> https://docs.perl6.org/language/exceptions
>>
>
>
> --
> brandon s allbery kf8nh
> allber...@gmail.com
>
Re: Exception Handling, DivideByZero
Two issues:
(1) all standard exceptions are in or under the X:: namespace.
(2) .WHAT doesn't show names with their namespaces, whereas .^name does.
pyanfar Z$ 6 'my $r = 4/0; say $r; CATCH {default {say .^name}}'
X::Numeric::DivideByZero
On Mon, Oct 29, 2018 at 1:04 PM Joseph Brenner 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
allber...@gmail.com
Exception Handling, DivideByZero
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
