Re: More Swift issues, NSURLComponents
Re: More Swift issues, NSURLComponents
- Subject: Re: More Swift issues, NSURLComponents
- From: Jens Alfke <email@hidden>
- Date: Mon, 05 Oct 2015 19:19:20 -0700
> On Oct 5, 2015, at 6:59 PM, Rick Mann <email@hidden> wrote:
>
> Huh. I continue to be bothered by the ambiguity/variability of "let"*. Is the reference immutable or the thing it points to?
A variable (var or let) doesn’t “point to” a struct. It _contains_ the struct. I.e. it’s a value, not a reference.
It’s just like in C or C++, really. Given a struct Foo,
const Foo x; // a value: x is immutable; you can’t change its fields
Foo* const x; // a reference: the variable x can’t be changed, but the Foo it points to can
The thing Swift doesn’t have that C/C++ do is
const Foo *x; // the Foo can’t be changed through this reference (though the value of x can)
The reason this was left out is probably that it doesn’t fit at all with Objective-C and the Cocoa frameworks, which have no concept of a constant reference to an NSObject.
—Jens
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