Re^5: RFC: Simulating Ruby's "yield" and "blocks" in Perl (Python)

[MonkOfAnotherSect]

v3 is current, though str.format() was added in late v2 releases for compatibility (printf style interpolation is to be deprecated some time but I'll use it below as an example...). Here's the decorated version as suggested:

Edit: trimmed some code

def rubyyielder(gen):
    def wrapped_gen(block):
        for elem in gen():
            block(elem)
    return wrapped_gen

@rubyyielder
def test():
    print("In test")
    yield 1
    print("back in test")
    yield 2

@test
def _(a):
    print("You are in block %s" % a)

I don't really see a win with this style, though, over giving test a parameter, and just using standard function calls (I had a little play with coroutines on the way but that's really overkill for this).

[LanX]

> I don't really see a win with this style, though, over giving test a parameter, and just using standard function calls (I had a little play with coroutines on the way but that's really overkill for this).

Well I expected decorators to be more flexible, i.e. to redefine test() by putting a wrapper around it and not to built a new decorator @test (!?!)

But I'm not too proficient with Python, and I'm misunderstanding the code.

(well, there must be a reason why I prefer Perl's syntactic flexibility. ;-)

I suppose def _(a) is a way to workaround the limitations of lamda?

Is the name _ special (magic) or is it just a convention?

[MonkOfAnotherSect]

(I've just trimmed the code back in http://perlmonks.com/?node_id=1030806 to use a closure rather than a class -- needed a class back when it was a coroutine... not so much anymore)

Here be Python...

Read more... (879 Bytes)

[LanX]

Thanx, it's clear now.

I was just surprised that you need two decorators!

I thought you could simply do something like

 test(def _(x): print("You are in block %s" % x))

(like  test sub { print("You are in block $_[0]") } in Perl)

Just to get closer to the Ruby feeling and to achieve this

>>> def _(x):
...     print("You are in block %s" % x)
... 
>>> test(_)
In test
You are in block 1
back in test
You are in block 2
test lambda a: print("You are in block %s" % a)

But one needs decorators to manipulate a literal function.

Obviously, there is only this way to do it.

FWIW Python decorators could quite easily be simulated in Perl with attributes.

I will post this soon (if I can't find it already on CPAN) =)