Outdated documentation for type conversions about julia HOT 4 CLOSED

Yes, once you use the Base convert function, you can't add a new function by the same name (as in the example above). You can only add methods to it. And to add methods to the function, you either need to import it, or fully qualify the name.

I think it's a good idea for the docs to be explicit about this, and add methods to Base.convert.

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Looks like it's working fine on v1.10.0.

julia> struct MyType
         value
       end

julia> convert(::Type{MyType}, x) = MyType(x)
convert (generic function with 1 method)

julia> convert(MyType, 1)
MyType(1)

julia> convert(MyType, pi)
MyType(π)

julia> versioninfo()
Julia Version 1.10.0
Commit 3120989f39 (2023-12-25 18:01 UTC)
Build Info:
  Official https://julialang.org/ release
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 32 × 13th Gen Intel(R) Core(TM) i9-13900HX
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-15.0.7 (ORCJIT, goldmont)
  Threads: 1 on 32 virtual cores

And latest doc already imports Base.convert at the beginning.
Maybe the doc update needs to be backported. (#50274)

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Whoops—I left out a step when I wrote the reproduction procedure, and never tried it again from a clean REPL! I've updated the procedure.

It turns out that before doing the original reproduction procedure, I tried to do an impossible conversion, like one of these:

convert(Int64, "a")

convert(Int64, 1.5)

This step is required to get the "invalid method definition" error later. Maybe this is expected behavior, although I certainly didn't expect it!

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Yes, once you use the Base convert function, you can't add a new function by the same name (as in the example above). You can only add methods to it. And to add methods to the function, you either need to import it, or fully qualify the name.

Aha! So, when @inkydragon pointed out that the original reproduction procedure "looks like it's working fine," that's actually an example of the silent failure I mentioned in the "Additional Context" section. The code runs without errors, but it doesn't add a method to Base.convert, which is what I thought would happen based on the uncorrected docs. I think @KristofferC's update resolves the confusion. 👍

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