pure or not pure?

[Leandro Lucarella]

Steven Schveighoffer, el 10 de abril a las 10:42 me escribiste:
> So let me restate: not having the ability to pass around UNIQUE mutable heap 
> data to and from pure functions is going to limit severely the usefulness of 
> pure functions.

This is the exact same problem of the mutable methods of a class used in a
stack allocated temporary of a pure function, talked in another thread.

class A {
	int x;
	void f() { x = 1; }
}

pure void g()
{
	scope a = new A;
	a.f();
}

g() is clearly pure (it has no side effects, besides allocating memory in
the stack, which shouldn't be considered a side effect, I guess allocating
in the heap shouldn't be considered a side effect either, since new is
thread safe). Even when A.f() is not pure, nor const.

There is an implementation problem, about how hard is to detect that by
the compiler, but in theory there is no reason for g() not being pure.

-- 
Leandro Lucarella (luca) | Blog colectivo: http://www.mazziblog.com.ar/blog/
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