[swift-evolution] [swift-evolution-announce] [Review] SE-0099: Restructuring Condition Clauses
ckornher at mac.com
Tue May 31 15:13:44 CDT 2016
> On May 31, 2016, at 1:59 PM, Brandon Knope <bknope at me.com> wrote:
> Except "b" is the main focus of the where clause and b was just in the preceding if condition.
> I feel like we are trying to find ways to break the current where clause even though we've enjoyed it for almost a year now. I had no idea it was problematic and restrictive. I thought it made its intent very clear...leading to very readable code.
> Pretty soon almost every construct but conditionals will be allowed to have where clauses, and THAT seems inconsistent to me.
> ...what exactly is the current problem? Can someone show me a real world example?? I've already forgotten it in all of this discussion -_-
I did this to explore why many people are reluctant to give-up ‘where’. The use of ‘where' seems intuitive to mess well, and I did not understand why. It seems to natural group all logic concerning a constant with its definition and this seems to be a way to do that.
These rules add restrictions, but it does group related elements. I am not convinced that this improves the language, but I though that it was worth exploring.
> On May 31, 2016, at 3:47 PM, Xiaodi Wu via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> On Tue, May 31, 2016 at 2:45 PM, Christopher Kornher via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> Not allowed:
>>> let a = a
>>> let b = b where b > 10 && a > 5
>>> Why would this not be allowed by your rule? You're making use of `b` in your where clause. As I demonstrated above, essentially any assertion can be rewritten to work around your rule. In general:
>> It is not allowed because ‘a’ is defined in the line above. It must be defined in the ‘if let’ associated with the where in which it is mentioned.
>> That's a much more restrictive where clause than you proposed earlier. You'd not be able to write:
>> let b = b where b > anyOtherVariable
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