[swift-evolution] Proposal: Re-instate mandatory self for accessing instance properties and functions

[Stephen Celis]

Are there warnings/diagnostics that could call out when local variables
shadow properties? I generally like that `self` is optional and prefer
limiting its use to explicitly call out potential retain cycles. Xcode also
makes it easy to introspect variable scope, though Xcode is less of a
requirement these days...

On Fri, Dec 4, 2015 at 5:34 PM, Rudolf Adamkovič <salutis at me.com> wrote:

> To be a little more specific, here’s a real-world example:
>
> 1. Say there’s a method in my class that contains a local variable called
> “title”.
> 2. After a while, I decide to remove a part of this method, including the
> “title” variable.
> 3. Everything compiles and seems to work just fine.
> 4. However, I forgot to remove one more line that used the “title”
> variable.
> 5. Because we’re in a UIViewController subclass, I'm unknowingly modifying
> view controller’s title.
>
> R+
>
> > On 4 Dec 2015, at 22:51, Rudolf Adamkovic <salutis at me.com> wrote:
> >
> > +1
> >
> > 1) I actually encountered at least two bugs in my app introduced by this
> implicit "self" behavior. It can be dangerous and hard to track down.
> >
> > 2) Also when, say fine-tuning UIKit animations, I find myself wasting
> enormous amount of time adding and removing "self".
> >
> > R+
> >
> > Sent from my iPhone
> >
> >> On 04 Dec 2015, at 22:19, David Hart <david at hartbit.com> wrote:
> >>
> >> I don't understand the reasoning behind removing the need to access
> instance properties and functions using self. Swift has always seemed to
> prefer readability to brevity and the feature makes the distinction between
> local and instance variables/functions crystal clear. Any good reason I
> shouldn't go on with the proposition?
> >>
> >> Just as example, my proposition makes the following piece of code
> illegal:
> >>
> >> ```
> >> struct FooBar {
> >>   var foo: String = "foobar"
> >>
> >>   func bar() {
> >>       print(foo) // compiler error
> >>       print(self.foo) // compiler happy
> >>   }
> >>
> >>   func bar2() {
> >>       bar() // compiler error
> >>       self.bar() // compiler happy
> >>   }
> >> }
> >> ```
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