I would strongly favor giving enums an own namespace. In C one often
repeats the enum name in the enum value in order to solve potential name
clashs.
Further it would be really cool to have enums in Base. I want to wrap a C
API where C enums are used to get/set values inside of objects and in that
situation enums would be really handy.
Am Donnerstag, 26. Dezember 2013 22:39:15 UTC+1 schrieb Stefan Karpinski:
>
> There is no @flags macro but it would be pretty easy to write, analogous
> to @enum.
>
> The real questions to me here are:
>
> 1. Should these be defined in a module so that they are Foo.BAR, etc.?
> 2. Should it by default be possible to dispatch on each value? I.e.
> should Foo be a parametric type and should BAR be the unique instance of
> Foo{0}?
>
>
>
> On Thu, Dec 26, 2013 at 4:36 PM, Stefan Karpinski
> <[email protected]<javascript:>
> > wrote:
>
>> It's pretty simple:
>>
>> julia> include("examples/enum.jl")
>>
>> julia> @enum Foo BAR BAZ QUX
>>
>> julia> Foo
>> Foo (constructor with 1 method)
>>
>> julia> BAR
>> BAR
>>
>> julia> BAZ
>> BAZ
>>
>> julia> QUX
>> QUX
>>
>> julia> isa(BAR,Foo)
>> true
>>
>> julia> isa(BAZ,Foo)
>> true
>>
>>
>> Foo is a type and BAR BAZ and QUX are constants bound to instances of it.
>>
>>
>> On Thu, Dec 26, 2013 at 4:26 PM, Marcus Urban <[email protected]<javascript:>
>> > wrote:
>>
>>> I don't quite understand how to use the @enum macro in examples/enum.jl.
>>> Could someone give an example that would have a similar effect to the C++
>>>
>>> enum class Fruit { Apple, Banana};
>>> auto f = Fruit::Apple;
>>>
>>> Also, there is the @flags macro provided?
>>>
>>>
>>>
>>> On Thursday, December 26, 2013 3:12:33 PM UTC-6, Stefan Karpinski wrote:
>>>
>>>> That's a good approach if you're going to dispatch on the types, but if
>>>> they're just values, we really should have something more like an enum. At
>>>> this point, I'm thinking that @enum and @flags are good macros to have –
>>>> where the @enum macro just defaults to 0, 1, 2, etc. while @flags defaults
>>>> to 1, 2, 4, 8, etc. and defines bitwise operations on the flag values.
>>>>
>>>>
>>>> On Thu, Dec 26, 2013 at 8:13 AM, andrew cooke <[email protected]>wrote:
>>>>
>>>>> great, thanks. a concrete example is just what i needed. andrew
>>>>>
>>>>>
>>>>> On Thursday, 26 December 2013 00:06:07 UTC-3, Kevin Squire wrote:
>>>>>
>>>>>> The julia sort code might provide some guidance. It follows your
>>>>>> last proposal, having an abstract type Algorithm, and a number of
>>>>>> concrete,
>>>>>> empty Algorithm subtypes (QuickSort, MergeSort, etc.), plus exactly one
>>>>>> global constant instance of each of these subtypes. So, as you
>>>>>> suggested,
>>>>>> there is a little bit of setup overhead, but it allows you to use the
>>>>>> "value" of the global constants for dispatch.
>>>>>>
>>>>>> Kevin
>>>>>>
>>>>>>
>>>>>> On Wed, Dec 25, 2013 at 4:45 PM, andrew cooke <[email protected]>wrote:
>>>>>>
>>>>>>> I want to parametrize some code, so that it does one of three
>>>>>>> different things, depending on the "value" of a parameter. The
>>>>>>> parameter
>>>>>>> is purely symbolic - there's no corresponding numerical value.
>>>>>>>
>>>>>>> There's an enum.jl in examples and also some discussion of related
>>>>>>> ideas in issues. But this isn't (yet) in the language, and anyway it
>>>>>>> seems
>>>>>>> crude (these are symbols, not numbers).
>>>>>>>
>>>>>>> There's also the possibility of using an abstract type and then
>>>>>>> three concrete subtypes. That seems like too much work but, as far as
>>>>>>> I
>>>>>>> can tell, is the way to "do" algebraic types in Julia (see list.jl
>>>>>>> example).
>>>>>>>
>>>>>>> I guess I am overthinking this. But what is the right approach?
>>>>>>>
>>>>>>> Thanks, Andrew
>>>>>>>
>>>>>>
>>>>>>
>>>>
>>
>
