[ruby-core:41738] Re: Documentation of the language itself (syntax, meanings, etc)

On Dec 19, 2011, at 3:04 PM, Rodrigo Rosenfeld Rosas wrote:
> Em 19-12-2011 19:38, Eric Hodel escreveu:
>> On Dec 15, 2011, at 7:39 PM, Rodrigo Rosenfeld Rosas wrote:
>>> Yeah, I already knew about all this. What I'm asking is why Ruby =
won't allow me to return from another method, ie, passing procs between =
different methods that will allow me to return from any method through =
that proc...
>>>=20
>>> I would like to know the reasoning behind this design decision... Is =
it just difficult technically to implement such behavior, or is it =
undesired? For the latter case, I would like to know why it is =
undesired...
>> Continuations allow you to arbitrarily unwind the stack, but you =
probably want to avoid using them because they're tricky to use =
correctly:
>=20
> Using global variables ($cont) in multi-threaded web servers is =
impractical, so it wouldn't work for what I'm looking for.

The global variable was simply an example, you can store continuations =
in any type of variable, constant, etc.

> In the other hand, catch-throw could work, but I would depend on the =
propose being accepted by the web framework being used, or maintaining =
some monkey patch myself, which I don't think would worth the extra =
"return"s saved.
>=20
> But don't get me wrong, I'm not insisting that Ruby should add support =
for such a feature. Actually, I've never asked for it, I was just =
wondering what are the reasons why this isn't supported by Ruby, but it =
was already pointed out to me that it could make code debugging very =
hard, which I agree=85

Continuations support what you want and much more, but due to the =
difficulty of debugging and understanding code using such constructs =
ruby does not support such a thing as a direct language feature.

You should be fortunate that you can implement the feature you want =
using continuations or catch/throw.  There are many other languages =
where implementation of such a feature would be vastly more difficult.

> I hope web frameworks will provide such feature by using some =
catch-throw implementation some day.

You will need to send feature requests.=