While I don't know how common it is in practice, if this migrates to Base we
might consider supporting BAZ=20 syntax (a pretty trivial addition, of
course).
--Tim
On Thursday, December 26, 2013 04:36:13 PM Stefan Karpinski 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]> 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
