I see that structs can have constructors, but can they also contain functions? I tried julia> mutable struct b; x::Int64; function y() x=22; end; end which gave no error, but b.y() does not work.

Short answer: No. You need to pass the this-pointer (mutables are de-facto pointers) explicitly, i.e. define function y(some_b::b) some_b.x=22; end; If this isn’t about syntactic sugar but name-spaces, consider writing a module where you would otherwise write a class with lots of methods (and then…

[image] vvjn: You could do the following… Don’t do this! using BenchmarkTools function Foo() x::Int = -1 setx(x_) = (x = x_) getx() = x () -> (getx;setx) end f = Foo() function fob(f, x) f.setx(x) end mutable struct Foo2 x::Int64 end function setx(a::…

the stack overflow example is interesting and unexpected, so let me repeat it: julia> function Person(name, age) getName() = name getAge() = age getOlder() = (age+=1) ()->(getName;getAge;getOlder) end Person (generic function with 1 method) julia> o = Person(…

Got curious, and it looks like f.setx is faster than python method calling. class Foo: def __init__(self): self.x = -1 def setx(self, x_): self.x = x_ if __name__ == '__main__': import timeit n = 10000000 t = timeit.timeit("f.setx(22)", setup="from __ma…

I strongly suggest you read this and this before designing anything that contains structs with functions as members. Multiple dispatch is a beautiful paradigm for writing code, it’s definitely worth getting familiar with it and how Julia instantiates it. I came to Julia for the performance, but it…

Also bear in mind that Julia 0.7 is slated to have simple get/set accessors for struct fields. So, there is little point in writing lots of those. Mainly I second @ExpandingMan - each language will have slightly different usage patterns, and Multiple Dispatch is amazing in use.

You could also do this… type Foo x::Int setx getx function Foo(x) f = new(x) f.setx = (x_) -> (f.x = x_) f.getx = () -> f.x f end end setx and getx are still slow but faster than the function one, …

In 0.7, this will be: mutable struct Foo x::Int end function Base.setproperty!(f::Foo, v, s::Symbol) if s == :x f.x = v else error("unknown property $s") end end function Base.getproperty(f::Foo, s::Symbol) if s == :x return f.x else error("…

[image] kristoffer.carlsson: And will have no performance penalty. I’m curious, this would seem to imply that Julia runs the setproperty! and getproperty functions at compile time. Otherwise, there certainly would be a performance penalty because running getproperty at run-time and checking …

The functions themselves can’t be run at compile time (you won’t know what e.g. f.x is when you compile) but all the branches and stuff will be gotten rid of since the symbol is a constant, and 0.7 have new fancy constant propagations spanning function boundaries.

Hi, could you update the link for your second reference were it is says “this” (101) ? It appears the link is broken. thanks in advance !

Do julia structs have member functions (and this->)

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rdeits October 26, 2021, 1:59pm 27

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Do julia structs have member functions (and this->)

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