juliadynamics / mixedstructtypes.jl Goto Github PK

E.g. say we have

using MixedStructTypes

abstract type AbstractShape end

@sum_structs Shape <: AbstractShape begin
    @kwdef struct Square
        side::Float64 = rand()
    end   
    @kwdef struct Rectangle
        width::Float64 = rand()
        height::Float64 = rand()
    end
    @kwdef struct Triangle
        base::Float64 = rand()
        height::Float64 = rand()
    end
    @kwdef struct Circle
        radius::Float64 = rand()
    end
end

currently we can define an area function like so:

function area(sh)
    if kindof(sh) === :Square
        area_square(sh)
    elseif kindof(sh) === :Rectangle
        area_rectangle(sh)
    elseif kindof(sh) === :Triangle
        area_triangle(sh)
    elseif kindof(sh) === :Circle
        area_circle(sh)
    else
        area_default(sh)
    end
end
   
area_square(s) = s.side * s.side
area_rectangle(r) = r.width * r.height
area_triangle(t) = 1.0/2.0 * t.base * t.height
area_circle(c) = π * c.radius^2
area_default(::AbstractShape) = 0.0

but actually we can generate all of this. So probably something like this should suffice

@dispatch area(s::Square) = s.side * s.side
@dispatch area(r::Rectangle) = r.width * r.height
@dispatch area(t::Triangle) = 1.0/2.0 * t.base * t.height
@dispatch area(c::Circle) = π * c.radius^2
@dispatch area(::AbstractShape) = 0.0

e.g. in the example in the readme, let's say only B has a special value

@dispatch value(::B) = 2

then it would be useful if this would also work to reduce verbosity:

@dispatch value(::A) = 1

which would mean that all other kinds have that value

Not sure if you were aware, didn't find any caveat mentioned.

I'm trying to incorporate @pattern in a package, and it works great, but loading extensions now fails. Offending line is

ERROR: LoadError: InitError: Evaluation into the closed module `FooModule` breaks incremental 
compilation because the side effects will not be permanent. This is likely due to some other 
module mutating `FooModule` with `eval` during precompilation - don't do this.

This would be breaking but it seems a better syntax which would allow more flexibility, it is also used in https://github.com/fredrikekre/EnumX.jl

Strangely it fails only on 1.8 with the struct_sum_type macro, it seems a convert problem in SumTypes.jl

CI run: https://github.com/JuliaDynamics/MixedStructTypes.jl/actions/runs/7647801175/job/20839415780

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I'll open a PR within a few hours, please be patient!

Unfortunately last pr #20 is not good enough

This can be done with an adaptation of the technique discussed in https://discourse.julialang.org/t/how-not-to-commit-type-piracy-when-handling-automatic-conversion-for-field-with-union-type/109877/5, thanks to @abraemer for the help