How to intercept module variable getting and setting in Julia 1.8 similar to getproperty and setproperty! for structures?

General Usage
1

Please help, how to intercept get and set variable of module in Julia 1.8 ?

julia> module M end;

julia> # in julia 1.9 i can do this:
julia> function Base.setproperty!(m::Module, p::Symbol, v)
           println("variable $p changed on $v in module $m")
           return setglobal!(m, p, v)
       end;

julia> # what about julia 1.8 ?

julia> M.x = 1;
variable x changed on 1 in module Main.M
2

That looks like a XY question, but:

julia> module M 
           x = 2
       end

julia> using .M

julia> M.x
2

julia> M.x = 1
1

julia> M.x
1
1 Like
3

Could you tell us more about what you are trying to do overall?

julia> module M end;

julia> M.x = 1
ERROR: cannot assign variables in other modules
Stacktrace:
 [1] setproperty!(x::Module, f::Symbol, v::Int64)
   @ Base .\Base.jl:32
 [2] top-level scope
   @ REPL[2]:1

julia> @eval M x = 1
1

julia> M.x
1
1 Like
4

oh sorry, my english is bad)

i need to override this as getproperty() and setproperty!() for structs

5 
julia> mutable struct Foo
           x::Int
       end

julia> import Base: setproperty!, getproperty

julia> setproperty!(value::Foo, name::Symbol, x) = setfield!(value, name, x*2)
setproperty! (generic function with 12 methods)

julia> foo = Foo(0)
Foo(0)

julia> foo.x = 5
5

julia> foo.x
10

julia> getproperty(value::Foo, symbol::Symbol) = symbol == :y ? 1 : getfield(value, symbol)
getproperty (generic function with 50 methods)

julia> foo.x
10

julia> foo.y
1
1 Like
6

thanks, but instead of Foo there must be module M

7

sorry for my english,

this is a solution:

function Base.setproperty!(m::Module, p::Symbol, v)
    println("variable $p changed on $v in module $m")
    @eval m $p = $v  # waiting for julia 1.9 and will use setglobal!()
end;
1 Like