Overriding a method in a different module

General Usage
1

Hi everyone, I am having trouble calling a method that I have overridden. Here is an example:

module XXX
    export hello
	function hello()
		println("XXX")
	end
end

using XXX

t = function XXX.hello()
    println("yyy")
end

t()

The result is:

WARNING: Method definition hello() in module XXX at test/overr.jl:4 overwritten in module Main at test/overr.jl:11.
ERROR: LoadError: MethodError: objects of type Void are not callable
Stacktrace:
 [1] include_from_node1(::String) at ./loading.jl:569
 [2] include(::String) at ./sysimg.jl:14
 [3] process_options(::Base.JLOptions) at ./client.jl:305
 [4] _start() at ./client.jl:371
while loading test/overr.jl, in expression starting on line 14
2

method definition in that form do not return a value. Just call the function direction or assign the function explicitly to the variable.

3

What do you mean?
can you show me a code example?
Thanks

4

It means typeof(function XXX.hello() ...end) == Void, so when you assigned to t, it gets the value nothing, hence cannot be called. So @yuyichao was suggesting to either call directly XXX.hello(), or to assign the function to a variable like in t = XXX.hello before calling t().

That said, I don’t know why this form of method definition unexpectedly returns nothing rather than the function.

5

It looks like you’re accidentally using R syntax to define a function.

6 
julia>	module XXX
	export hello
	function hello()
		println("XXX")
	end
	end

julia> using XXX

julia>	t = function XXX.hello()
		println("yyy")
	end

julia> typeof(t)
Void

julia>	XXX.hello()
yyy