From @lizmat

Should this work? If not, why not? What would be the way to inherit from lexical classes in other compunits?

./A.pm6​:
my class A {}

./B.pm6​:
my class B {
  use A;
  also is A;
}

$ PERL6LIB=. 6 'use B'
===SORRY!=== Error while compiling /Users/liz/Github/rakudo.moar/B.pm6 (B)
Invalid typename 'A'
at /Users/liz/Github/rakudo.moar/B.pm6 (B)​:4
------> also does A⏏;

From @zoffixznet

To the best of my knowledge​:

On Thu, 18 May 2017 03​:52​:42 -0700, elizabeth wrote​:

Should this work? If not, why not?

No, because the symbol is lexical to the compunit. It's the same as how you won't be able
to access subs or `my` constants or variables, unless you make them `our` or export them.

What would be the way to inherit from lexical classes in other compunits?

One way would be to export them​:

./A.pm6​:
my class A is export {}

./B.pm6​:
my class B {
  use A;
  also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
((B) (A) (Any) (Mu))

You can also use export sub​:
./A.pm6​:
sub EXPORT {
  Map.new​: 'A' => my class A {}
}

Or (I'm unsure what the end goal here is), take a special export arg and only export the class if it's present​:

./A.pm6​:
sub EXPORT ($secret-password?) {
  Map.new​: (
  'A' => my class A {
  } if $secret-password ~~ 42
  )
}

./B.pm6​:
my class B {
  use A;
  also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
===SORRY!=== Error while compiling /home/zoffix/CPANPRC/rakudo/B.pm6 (B)
'B' cannot inherit from 'A' because it is unknown.
at /home/zoffix/CPANPRC/rakudo/B.pm6 (B)​:3

Now change ./B.pm6 to​:
my class B {
  use A 42;
  also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
((B) (A) (Any) (Mu))

The RT System itself - Status changed from 'new' to 'open'

From @LLFourn

FWIW theoretically you get at any 'my' symbol in another module through the
compunit interface by getting the CompUnit​::Handle and using the '.unit'
method to get the top lexpad of the loaded module.

On Fri, May 19, 2017 at 8​:20 AM Zoffix Znet via RT <
perl6-bugs-followup@​perl.org> wrote​:

To the best of my knowledge​:

On Thu, 18 May 2017 03​:52​:42 -0700, elizabeth wrote​:

Should this work? If not, why not?

No, because the symbol is lexical to the compunit. It's the same as how
you won't be able
to access subs or `my` constants or variables, unless you make them `our`
or export them.

What would be the way to inherit from lexical classes in other compunits?

One way would be to export them​:

./A.pm6​:
my class A is export {}

./B.pm6​:
my class B {
use A;
also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
((B) (A) (Any) (Mu))

You can also use export sub​:
./A.pm6​:
sub EXPORT {
Map.new​: 'A' => my class A {}
}

Or (I'm unsure what the end goal here is), take a special export arg and
only export the class if it's present​:

./A.pm6​:
sub EXPORT ($secret-password?) {
Map.new​: (
'A' => my class A {
} if $secret-password ~~ 42
)
}

./B.pm6​:
my class B {
use A;
also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
===SORRY!=== Error while compiling /home/zoffix/CPANPRC/rakudo/B.pm6 (B)
'B' cannot inherit from 'A' because it is unknown.
at /home/zoffix/CPANPRC/rakudo/B.pm6 (B)​:3

Now change ./B.pm6 to​:
my class B {
use A 42;
also is A;
}
say B.^mro;

$ ./perl6 -I. -MB -e ''
((B) (A) (Any) (Mu))

From @jnthn

On Thu, 18 May 2017 15​:19​:26 -0700, cpan@​zoffix.com wrote​:

To the best of my knowledge​:

On Thu, 18 May 2017 03​:52​:42 -0700, elizabeth wrote​:

Should this work? If not, why not?

No, because the symbol is lexical to the compunit. It's the same as
how you won't be able
to access subs or `my` constants or variables, unless you make them
`our` or export them.

This and the rest of the response are correct; ticket rejected as there's no bug here. The point of lexical stuff in modules is that it's not visible outside unless explicitly exported.

@jnthn - Status changed from 'open' to 'rejected'