On Wednesday, July 24, 2013 12:40:01 PM David Korn wrote:
> cc: [email protected] [email protected]
> Subject: Re: Re: [ast-users] _ doesn't refer to the correct object.
> --------
>
> > What happens if "x" itself is a typed variable? What does python do?
>
>
> I don't know what python does. What I did for ksh was to have _ reference
> x when x is a type variable.
Ksh has "type variables"? As in generics?
If you really mean "objects", in Python, everything is an object and has a
type. There are no "untyped variables". Why wouldn't Ksh's _ work the same for
user-defined types as for built-in types?
#!/usr/bin/env python3
class A(object):
def __init__(self):
self.y = "I'm from A"
@property
def x(self):
return self.y
class B(A):
def __init__(self, **kwargs):
self.y="I'm from B"
print(self.x) # "I'm from B"
super().__init__(**kwargs) # call base class
constructor.
obj = B()
print(obj.x) # "I'm from A"
I take it that __ is going to work like super(), hopefully. This basic program
fails in several ways:
#!/usr/bin/env ksh
typeset -T Person_t=(
integer -S population
typeset name
function create {
((_.population++))
}
# This destructor fails altogether for some reason.
function unset {
((_.population--))
}
# Static method
typeset -fS totalpop
function totalpop {
printf 'Total population is currently %d.\n'
"${_.population}"
}
)
typeset -T Maintainer_t=(
Person_t _
function create {
# We need some equivalent to Python super().
# Theres no base class access or virtual / override
methods.
.sh.type.Person_t.create
.sh.type.Person_t.totalpop
}
# I don't know whether this is needed. It fails either way.
function unset {
.sh.type.Person_t.unset
.sh.type.Person_t.totalpop
}
)
typeset -T Shell_t=(
Maintainer_t -a maintainers
typeset list
function create {
print -r 'Another UNIX shell?!'
}
)
function main {
compound shells=(
Shell_t ksh=(maintainers=((name=DGK) (name=Glenn));
list=ast-users)
Shell_t bash=(maintainers=((name=Chet)); list=bug-bash)
Shell_t mksh=(maintainers=((name=TG)))
)
typeset -p shells
unset -v shells
}
main "$@"
--
Dan Douglas
_______________________________________________
ast-users mailing list
[email protected]
http://lists.research.att.com/mailman/listinfo/ast-users
