Non-32-bit enums / "Typed" enums #18826

nbaum · 2016-10-07T03:27:40Z

Adds @enum Foo::*IntegerType* to specify to use a bitstype with the same size as the specified integer type. The default type remains Int32.

Use case: I want to use an enum for a field in a structure passed to a C function, and I don't get to decide the field size.

Summary:

The type must be an integer bitstype.
read and write read/write the right number of bytes.
convert(Integer, value) converts into the type specified in the @enum. Converting to a specific integer types works the same way as before.
There's no accessor to determine the specified type, but typeof(convert(Integer, value)) will do.
Some of the old typed enums tests have been updated, but many of them relate to the val field, which isn't really meaningful now.

Tangentally related changes:

names is overloaded for enums, and returns the names of the enumerants. Not totally sure that is the right function for the concept, though.

Not done (yet):

Updating documentation for @enum.

Unanswered questions:

What should this be called? "Typed enum" seems clear, but enums already have types.

nbaum · 2016-10-07T03:29:28Z

base/Enums.jl

    vals = Array{Tuple{Symbol,Integer}}(0)
    lo = hi = 0
-    i = Int32(-1)
+    i = zero(basetype)


I switched this from incrementing before a symbol to incrementing afterward because that seemed to be the clearest way to support unsigned base types.

nbaum · 2016-10-07T03:30:08Z

base/Enums.jl

    hasexpr = false
    for s in syms
        if isa(s,Symbol)
-            if i == typemax(typeof(i))
+            if i == typemin(basetype) && !isempty(vals)


It must have wrapped if it's the typemin and there was a previous iteration.

nbaum · 2016-10-07T03:31:25Z

base/Enums.jl

+        Base.convert(::Type{Integer}, x::$(esc(typename))) = box($(basetype), x)
+        Base.convert{T<:Integer}(::Type{T}, x::$(esc(typename))) = convert(T, box($(basetype), x))
+        Base.write(io::IO, x::$(esc(typename))) = write(io, $(basetype)(x))
+        Base.read(io::IO, ::Type{$(esc(typename))}) = $(esc(typename))(read(io, $(basetype)))


I didn't see a way to make these work without overloading them for each enum type. I toyed with making Enum itself generic, but that broke everything in fun ways.

I'd like to hear more about that, as having Enum{T} seems like a nice way to get this if possible.

nbaum · 2016-10-07T03:37:35Z

base/Enums.jl

@@ -130,9 +143,9 @@ macro enum(T,syms...)
            end
        end
    end
-    if isa(T,Symbol)


By my reading of the code this can't ever be false.

You're right; I think that's a vestige from when enums could have type parameters.

nbaum · 2016-10-07T03:37:36Z

base/Enums.jl

@@ -130,9 +143,9 @@ macro enum(T,syms...)
            end
        end
    end
-    if isa(T,Symbol)
+    if isa(typename,Symbol)


But I kept it here just in case I missed something.

nbaum · 2016-10-07T03:38:25Z

test/enums.jl

@@ -81,59 +81,20 @@ end
 @test_throws ArgumentError eval(:(@enum Test22 1=2))

 # other Integer types of enum members
-# TODO - not yet supported


A lot of these .val related tests don't really make sense with bitstype-based enums.

nbaum

Some comments

JeffBezanson · 2016-10-11T18:22:37Z

base/Enums.jl

        let insts = ntuple(i->$(esc(typename))($values[i]), $(length(vals)))
            Base.instances(::Type{$(esc(typename))}) = insts
        end
+        Base.names(::Type{$(esc(typename))}) = $(esc(names))


I would not add this in this commit, as it's not really related AFAICT.

JeffBezanson · 2016-10-11T18:23:37Z

base/Enums.jl

@@ -130,9 +143,9 @@ macro enum(T,syms...)
            end
        end
    end
-    if isa(T,Symbol)


You're right; I think that's a vestige from when enums could have type parameters.

JeffBezanson · 2016-10-11T18:25:22Z

base/Enums.jl

+        Base.convert(::Type{Integer}, x::$(esc(typename))) = box($(basetype), x)
+        Base.convert{T<:Integer}(::Type{T}, x::$(esc(typename))) = convert(T, box($(basetype), x))
+        Base.write(io::IO, x::$(esc(typename))) = write(io, $(basetype)(x))
+        Base.read(io::IO, ::Type{$(esc(typename))}) = $(esc(typename))(read(io, $(basetype)))


I'd like to hear more about that, as having Enum{T} seems like a nice way to get this if possible.

JeffBezanson · 2016-10-11T18:28:15Z

base/Enums.jl

+        Base.convert(::Type{Integer}, x::$(esc(typename))) = box($(basetype), x)
+        Base.convert{T<:Integer}(::Type{T}, x::$(esc(typename))) = convert(T, box($(basetype), x))
+        Base.write(io::IO, x::$(esc(typename))) = write(io, $(basetype)(x))
+        Base.read(io::IO, ::Type{$(esc(typename))}) = $(esc(typename))(read(io, $(basetype)))


The earlier definitions of convert, read, and write in this file should be removed.

I had another go at doing Enum{T} and the problems I had last time didn't reappear. So that's nice.

I didn't see a way to implement Base.read without a helper method to extract the type, which I think is a bit unfortunate. In principle I want to do

Base.read{EnumT<:Enum{T<:Integer}}(io::IO, ::Type{EnumT}) = EnumT(read(io, T))

but we don't have triangular dispatch yet. :)

simonbyrne · 2016-11-21T09:34:29Z

I think this is a good idea: would you mind updating the docs?

simonbyrne · 2016-11-30T16:36:50Z

base/Enums.jl

    if hasexpr && values != unique(values)
        throw(ArgumentError("values for Enum $typename are not unique"))
    end
    blk = quote
        # enum definition
-        Base.@__doc__(bitstype 32 $(esc(T)) <: Enum)
+        Base.@__doc__(bitstype $(basetype.size * 8) $(esc(typename)) <: Enum{$(basetype)})


this should probably be sizeof(basetype)

simonbyrne · 2016-12-01T09:58:37Z

base/Enums.jl


-Base.convert{T<:Integer}(::Type{T}, x::Enum) = convert(T, box(Int32, x))
+abstract Enum{T<:Integer}


I guess we need to think about whether or not it makes sense to have Enum be a parametric type.

I did it this way because Jeff said it'd be nice. I'm not attached either way, although it does seem elegant to me.

OTOH, if it is parametric, a nice but incompatible option would be to parameterize on bits length. I can imagine some codec package - e.g. for ASN - finding it convenient to refer to the type of enums that are N bits long.

Adds `@enum Foo::*IntegerType*` to specify to use a bitstype with the same size as the specified integer type. The default type remains `Int32`. Summary: * The type must be an integer bitstype. * `read` and `write` read/write the right number of bytes. * `convert(Integer, value)` converts into the type specified in the `@enum`. Converting to a specific integer types works the same way as before. * There's no accessor to determine the specified type, but `typeof(convert(Integer, value))` will do. * Some of the old typed enums tests have been updated, but many of them relate to the `val` field, which isn't really meaningful now. Tangentally related changes: * `names` is overloaded for enums, and returns the names of the enumerants. Not totally sure that is the right function for the concept, though.

tkelman · 2016-12-29T19:19:46Z

test/enums.jl

-@test typeof(_zero_Test7.val) <: UInt8
-
-@test_throws ArgumentError eval(:(@enum Test8 _zero="zero"))
-@test_throws ArgumentError eval(:(@enum Test9 _zero='0'))


why is it that these don't throw now?

Oops. They still do. I deleted too many lines when removing the .val tests.

tkelman · 2016-12-30T18:35:49Z

base/Enums.jl


-Create an `Enum` type with name `EnumName` and enum member values of
+Create an [`Enum`]{`BaseType`} subtype with name `EnumName` and enum member values of


what are you going for with the formatting here?

tkelman · 2016-12-30T18:36:48Z

base/Enums.jl

@@ -42,33 +44,42 @@ f (generic function with 1 method)
 julia> f(apple)
 "I'm a FRUIT with value: 1"
 ```
+
+`BaseType`, which defaults to `Int32`, must be a bitstype subtype of Integer. Member values can be converted between
+the enum type and `BaseType`. `read` and and `write` perform these conversions automatically.


"and and" repeated

nbaum commented Oct 7, 2016

View reviewed changes

JeffBezanson requested changes Oct 11, 2016

View reviewed changes

simonbyrne added this to the 0.6.0 milestone Nov 21, 2016

simonbyrne reviewed Nov 30, 2016

View reviewed changes

simonbyrne reviewed Dec 1, 2016

View reviewed changes

simonbyrne mentioned this pull request Dec 2, 2016

RFC: EnumSet type #19470

Closed

nbaum added 4 commits December 29, 2016 00:27

Tests for typed @enums

a46b306

Documentation

81f71e1

basetype.size => sizeof(basetype)

3fafd39

JeffBezanson approved these changes Dec 29, 2016

View reviewed changes

JeffBezanson merged commit 229d096 into JuliaLang:master Dec 29, 2016

tkelman reviewed Dec 29, 2016

View reviewed changes

tkelman reviewed Dec 30, 2016

View reviewed changes

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Non-32-bit enums / "Typed" enums #18826

Non-32-bit enums / "Typed" enums #18826

nbaum commented Oct 7, 2016

nbaum Oct 7, 2016

nbaum Oct 7, 2016

nbaum Oct 7, 2016

JeffBezanson Oct 11, 2016

nbaum Oct 7, 2016

JeffBezanson Oct 11, 2016

nbaum Oct 7, 2016

nbaum Oct 7, 2016

nbaum left a comment

JeffBezanson Oct 11, 2016

nbaum Oct 11, 2016

JeffBezanson Oct 11, 2016

JeffBezanson Oct 11, 2016

JeffBezanson Oct 11, 2016

nbaum Oct 11, 2016

simonbyrne commented Nov 21, 2016

simonbyrne Nov 30, 2016

simonbyrne Dec 1, 2016

nbaum Dec 2, 2016

tkelman Dec 29, 2016

nbaum Dec 30, 2016

tkelman Dec 30, 2016

tkelman Dec 30, 2016


		Base.convert{T<:Integer}(::Type{T}, x::Enum) = convert(T, box(Int32, x))
		abstract Enum{T<:Integer}


		Create an `Enum` type with name `EnumName` and enum member values of
		Create an [`Enum`]{`BaseType`} subtype with name `EnumName` and enum member values of

Non-32-bit enums / "Typed" enums #18826

Non-32-bit enums / "Typed" enums #18826

Conversation

nbaum commented Oct 7, 2016

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

nbaum left a comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

simonbyrne commented Nov 21, 2016

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment