Is it possible to overload +=? mutable struct A a::Int end function Base.:+=(a::A, b::A) a.a += b.a a end EDIT: As pointed out by @giordano in post 7 , the struct A should be defined immutable: struct A a::Int end

You can’t overload assignment, but I think it’s enough in this case to overload + and += will come for free.

Thank you for the quick reply but it does not seem to work: julia> Base.:+(a::A, b::A) = A(a.a+b.a) julia> A(2) + A(3) A(5) julia> A(2) += A(3) ERROR: syntax: invalid assignment location "A(2)" around REPL[12]:1 Stacktrace: [1] top-level scope @ REPL[12]:1

[image] mzaffalon: julia> A(2) += A(3) This is basically the same as julia> 1 += 2 which of course doesn’t work.

But the sum should not mutate neither argument: it is only += that should. Am I wrong?

Assignment, including +=, never mutates. Is this what you were expecting?

How to overload +=?

General Usage

giordano November 15, 2021, 8:03pm 7

Note that this wouldn’t mutate the argument (which one?), in case this is what you were expecting, since you marked the type as mutable.

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How to overload +=?

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