Hello,
15-07-2009, 09:55 Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> One such extension might be a "where" block. Applied
> to the current problem:
>
> foo(f) where:
> def f(x):
> ...
At first glance, +1 from me.
15-07-2009, 12:25 Paul Moore <p.f.moore at gmail.com> wrote:
> inside the [...] - which clearly violates the "no indented block
> structure within expressions" design rule.
>
> My initial instinct was that the original form violated that rule, too
> - but if you interpret the where block as a statement postfix, you're
> (almost) OK. The (almost) bit is because the where block has to be
> limited to simple (single-line) statements.
> stmt where:
> a
> b
> c
> =>
>
> a
> b
> c
> stmt
>
> with the proviso that variables defined in a,b,c are only available
> within a, b, c and stmt.
I don't like the direction of limiting content of the block to set of
singular simple statements. I suppose where-block should simply create a
separate nested scope.
So...
> x = 1
> y = x where:
> x = 2
> print x
>
> What does that print?
I tkink it should print 1 -- because, if where-block creates a separate
nested scope, its local variables shouldn't leak.
But there is another question: what is the value of y: 1 or 2? Or, more
genarally: should be the line ended with 'where' included *in* that nested
scope or not? I suppose it should, so the final value of y should be 2.
Another example:
a = 7
b = 8
x = 'X'
z = 'zzzzz'
foo(a, b, c("It's..."), x) where:
# a = input() in Python 3.x :)
a = raw_input(z) # -> zzzzz
try:
a = int(a)
except ValueError:
a = 0
def b(bar):
'very complex function'
print(a, bar)
else:
def b(bar):
'also very complex function'
print(bar, a, bar)
def c(*args, **kwargs):
'also also very complex function'
print(a, b) # -> 7 8
Best regards,
--
Jan Kaliszewski <zuo at chopin.edu.pl>