raku my class scoping examples

P.rakumod

CASE 1
------

# this is in file lib/P.rakumod
package P { 
  class A is export { has $.a = 42 }
}

# this is in file test.raku
use P;
A.new.a.say

# run it with
> raku -I'./lib' test.raku    #42

-or-

CASE 2
------

we can simplify the package file so that it only contains classes like this:
note that the default is that the class declaration is our scoped so that you do not have to muddy this really clean model with is export traits

# this is in file lib/P.rakumod
class A { has $.x = 42 }

# this is in file test.raku
use P;
A.new.x.say

# run it with
> raku -I'./lib' test.raku

42

-or- 

CASE 3
------

we can have multiple classes in the package file

# this is in file lib/P.rakumod
class A { has $.x = 42 }
class B { has $.x = 43 }

# this is in file test.raku
use P;
A.new.x.say
B.new.x.say

# run it with
> raku -I'./lib' test.raku

42
43

-and-

CASE 4
------

in this case we may want to distinguish between publically available classes that form the API and private classes that 
are implementation details that we reserve the right to change

# this is in file lib/P.rakumod
my class X { has $.x = 44 }
class A { has $.x = 42 }
class B { has $.x = 43 }
class C is X { };

# this is in file test.raku
use P;
A.new.x.say
B.new.x.say
C.new.x.say
X.new.x.say

# run it with
> raku -I'./lib' test.raku

42
43
44
You cannot create an instance of this type (X)
  in block <unit> at scum.raku line 5