conflict with previous value in same-name Shadowing

Question

I'm reading from Erica Sadun's Swift Style book and playing around with some code.

She suggests:

Prefer using same-name shadowing in conditional bind. “This approach is both conventional and safe:

guard let x = x { ... } // yes

guard let y = x { ... } // no

Deliberate same-name shadowing ensures the the unwrapped value’s role follows the logical intent established by the name prior to the if or guard statement. Introducing a new name blurs the line of those semantics and can prove dangerous. Consistent same-named shadowing prevents you from adding an unintentional shadow to symbols in the parent scope.

Regardless of this being a good opinion or not:

In my code, I'm trying to do:

guard let data = data else{...}

but I get the following error:

Definition conflicts with previous value

A simplified version of my function is:

func process(){
  data : AnyObject?

  if x == nil{ data = m}
  else if x > 5{ data = j}
  guard let data = data else { return } // Definition conflicts with previous value
  somefunc(data)
}

If I place the guard statement inside the if or else if then the error would go away. But that's not what I want.

Is there any workaround to still be able to do same-name shadow.

EDIT: I tried using backticks and I get the following errors:

Expected Pattern

Braced block of statements is an unused closure

try `guard let ``data`` = data` <- data in "`", dunno how to avoid stack overflow forcing them to be code borders — JuicyFruit, Mar 28 '17 at 15:53
@JuicyFruit do you mean place 2 backticks before and after the first `data`? I tried. Didn't work. Got a different error. See my edit — mfaani, Mar 28 '17 at 15:59
1 backtick each side, didn't know how this symbol is called, sry — JuicyFruit, Mar 28 '17 at 16:00
@JuicyFruit I still get error: Definition conflicts with previous value — mfaani, Mar 28 '17 at 16:01
Also see http://stackoverflow.com/questions/41854162/when-did-guard-let-foo-foo-become-legal — rmaddy, Mar 28 '17 at 16:06
@rmaddy this embarrassing. I've already mentioned that exactly in my **own** answer [here](http://stackoverflow.com/a/39263210/5175709). See The part where I say: "Guard creates a new variable" — mfaani, Mar 28 '17 at 16:08
Are you sure Erica isn't talking about `if let` and not `guard let`? — rmaddy, Mar 28 '17 at 16:10
@rmaddy yes 100% sure. That code snippet is copy/pasted from her book — mfaani, Mar 28 '17 at 16:11
You might want to format the book quotes using > so it shows as a quote. — rmaddy, Mar 28 '17 at 16:12
@rmaddy to be precise she mentions it for both `if let` & `guard let` — mfaani, Mar 28 '17 at 16:13

conflict with previous value in same-name Shadowing

0 Answers0