[swift-evolution] Making capturing semantics of local

[Mike Kluev]

On 26 October 2017 at 20:24, David Hart <david at hartbit.com> wrote:

> I don’t see how this makes any sense or be possible:
>
> * It doesn’t make sense for me because local is not a member function of A.
> * It would cause ambiguity when trying to call another member function
> with the same name as the local function.
>

in the escaping contexts, "self." is currently required before the instance
members (**).
the idea is to require it before some local functions as well, recursively
analysing what these local functions do (at the compile time).

/* local */ foo() {
    bar()
    variable = 1
}

...
self.foo()

// self is required because the compiler knows what's inside, and if it
were to put the content inline that would be:

// inlining foo pseudo code:
     self.bar()
     self.variable = 1

hence the compiler can figure out that in this case "self" is required
before foo()

on the other hand:

/* local */ poo() {
    print("doesnt not capture anything")
}

here, if compiler were to use poo in the escaping context it would not
require "self." before it.

this decision (whether to require "self." on not) can be on the use side.

(**) FTM, the normal instance methods that do not capture anything may as
well not require "self." before them in escaping contexts:

/* non local */ baz() {
    print("doesn't capture anything")
}

Mike
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