Consider the following: foo(x) = x foo_type = foo |> typeof # Don't know how to implement but I know what I want it to do # Example: default(foo_type) -> foo default(::Type{T}) where T <: Function = ??? # The following code works but is not generic default(::Type{foo_type}) = foo How can I imple…

As I said in the linked discussion though, if you want to ignore those corner cases, you can write something like function default(::Type{ft}) where {ft <: Function} if isdefined(ft, :instance) ft.instance else error("This type does not have a single instance") end end …

Here you go: [image] How to get a function instance from a function type? Internals & Design No, because not all functions have a one-to-one relationship with their types. For instance, f = let x = 1 y -> x + y end captures runtime data and cannot be reconstructed fr…

The second hardcoded version works even if there are multiple instances of the function. Namely I am not looking to get back a specific method of the function but rather the function itself which does have a 1 to 1 relationship with the type

[image] HashBrown: Namely I am not looking to get back a specific method of the function but rather the function itself which does have a 1 to 1 relationship with the type I wasn’t talking about methods, I was talking about functions themselves. One function type can have multiple instances i…

Ah I see. Sorry I thought methods and instances were the same, but thank you for correcting me on that. I think I should be fine not being able to handle that corner case. Thanks

Actually a follow up. In my case I just need a value of the type. In other words it does not have to be any particular instance, just an instance. So even if there is not a 1-1 matching that would be fine for me. Is there a way to get an instance regardless of whether it is a single instance or not…

@HashBrown Do you mind if I ask what are you actually trying to do here? It may be that there’s a smarter way to get what you want here… Regardless though, yes, it is in fact possible for you to get a instance of any type (including functions) which uninitialized values in any slots. Doing this re…

I noticed that any_instance(Tuple{Int64, String}) is crashing Julia. Is that expected? As for what I am working on, it is rather hard to explain. But basically I am creating a bunch of const Ref types in global scope and functions that control access to them through metaprogramming (another thing I…

[image] HashBrown: I noticed that any_instance(Tuple{Int64, String}) is crashing Julia. Is that expected? It’s not crashing julia. Trying to diplay it in the REPL is crashing julia. julia> let x = any_instance(Tuple{Int, String}) dump(x) end Tuple{Int64, String} 1: Int64 …

I edited the above to include a follow up question. Sorry, I should have posted it as a reply, but I think I edited it while you were responding.

[image] HashBrown: Also on the implementation of new I am not really following what args... is doing. When I write: struct Foo a::Int64 end Expr(:new, Foo) |> eval # ERROR: invalid struct allocation Which to me seems like it should work based on your function definitions. Obviously the …

Extract function from function type

General Usage

Mason November 22, 2022, 4:31pm 2

Here you go:

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Extract function from function type

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