[swift-evolution] class indent in swift, history?

[Derrick Ho]

It might have to do with C history. Anything inside two curly braces
usually had an increased indentation level.

I always thought the switch statement was an oddball for not indenting the
cases.
On Tue, Mar 7, 2017 at 1:42 AM Will Stanton via swift-evolution <
swift-evolution at swift.org> wrote:

> Hello Chris and perhaps core team members,
>
> The comments on tab-levels for `switch` made me want to ask about the
> considerations that went into class and protocol-level indentation.
>
> Sorry if my wording isn’t precise, but in Objective-C, functions can
> (should) be at the same 0-indent level as the class:
> @implementation Foo
> // No indent!
> - (void)doSomething {
> }
> @end
>
> However, in Swift, method and nested types are indented by default:
> class Foo : Bar {
>         // Things indented!
>         enum Types {
>         }
>         func doSomething() {
>         }
> }
>
>
> Was the change mostly driven by the desire for protocol+class+struct+enum
> consistency in ‘increasing’ the scope+indent level? Were there other
> considerations?
> Why didn’t the language evolve into something like this to reduce the use
> of horizontal whitespace, allowing class functions/types at the root/top
> level? Like:
> @class Foo : Bar
> enum Types {
> }
> func doSomething() {
> }
> @end
>
>
> Regards,
> Will Stanton
>
> > On Mar 7, 2017, at 12:52 AM, Chris Lattner via swift-evolution <
> swift-evolution at swift.org> wrote:
> >
> > I can understand how you might find this unnerving, but it is important
> to understand that Swift and Objective-C/C have different semantics when it
> comes to case labels:  in Swift, a case label *is* a scope, and *is* part
> of the switch statement.  In Objective-C, a case label is just a label,
> like any other goto label: it is not a scope and is not necessarily a
> direct child of the switch statement.
> >
> > C and Objective-C’s behavior is what leads to obscure but important
> things like Duff’s device (https://en.wikipedia.org/wiki/Duff's_device).
> >
> > In contrast, Swift fixes the scoping, fallthrough, and other related
> problems all in one fell swoop, and ensures that cases are directly nested
> under the switch (unlike in C, where they can be nested under other
> statements within the switch).  Because the case/default labels are *part
> of* the switch in Swift, it makes sense for them to be indented at the same
> level.
> >
> > While I can respect that you aesthetically have a preference for the
> Objective-C way of doing things, the rationale for this behavior change
> wasn’t arbitrary and wasn’t due to "LLVM style".  It is an important
> reflection of the core semantics of the language model.
> >
> > Finally, conservation of horizontal whitespace is important for
> comprehension of code, particularly w.r.t. readability and maintenance.
> This is why statements like guard exist: to reduce nesting and indentation,
> directing the attention of someone reading and maintaining code to the
> important parts.
> >
>
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