Enum literals, good? bad? what do you think?

Walter Bright newshound2 at digitalmars.com
Wed Jul 21 06:39:18 UTC 2021

On 7/20/2021 9:12 AM, H. S. Teoh wrote:
> OTOH, I agree that sometimes D enums become rather verbose. Especially
> in switch statements where you have to repeat their name for every case.
> Fortunately, this is where D's `with` statement comes in helpful:
> 	enum MyEnum { blah, bleh, bluh }
> 	MyEnum val = ...;
> 	final switch (val) {
> 		case MyEnum.blah: ...
> 		case MyEnum.bleh: ...
> 		case MyEnum.bluh: ...
> 	}

In C, qualifying the member name with the tag name is not only not necessary, it 
is not allowed. Hence, here how C does it:

         enum MyEnum { MyEnum_blah, MyEnum_bleh, MyEnum_bluh };
	enum MyEnum val = ...;
	switch (val) {
		case MyEnum_blah: ...
		case MyEnum_bleh: ...
		case MyEnum_bluh: ...

It's not very attractive. C++ eventually added some more syntax so the members 
had to be qualified. This is because once the project exceeds a certain level of 
complexity, qualifying those enum member names becomes desirable.

But if you still want unqualified names, `alias` is the feature:

     enum MyEnum { blah, bleh, bluh }
     alias blah = MyEnum.blah;
     alias bleh = MyEnum.bleh;
     alias bluh = MyEnum.bluh;

`alias` is an all-purpose tool for moving names from one scope to another. Of 
course, one can probably do a mixin to automate the alias declarations. It 
should be a fun exercise. Any takers?

(As mentioned by others, `with` does it too, but `with` only affects the scope 
it specifies.)

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