ConferenceCall
ConferenceCall.jl allows multiple methods to be defined with
the "same" signature (some Val{unique_key} is added behind the scene to make them
different). Calls to that function will call all applicable methods, and return their
results in a Vector.
@confcall function ask_for_advice end
@confcall ask_for_advice() = "Buy!"
@confcall ask_for_advice() = "Sell!"
@confcall ask_for_advice(whom::String) = "I didn't say anything"
julia> ask_for_advice()
2-element Array{String,1}:
"Sell!"
"Buy!"
julia> ask_for_advice("Harry")
1-element Array{String,1}:
"I didn't say anything"
julia> ask_for_advice(:BobSymbol)
0-element Array{Union{},1}The methods are called in sorted order, based on the optional key passed as first argument:
@confcall function describe_object end
@confcall 1 describe_object(x) = "Something"
@confcall 2 describe_object(x::Number) = "Some number"
@confcall 3 describe_object(x::Int) = "An Int"
julia> describe_object(3.0)
2-element Array{String,1}:
"Something"
"Some number"Keys can be Numbers or Symbols.
Because it is based on plain Julia methods, @confcall is precompilation-friendly and
Reviseable. It can be useful for macros
that register callbacks.
Making a conference call is moderately slow, as it involves some reflection.
julia> @btime describe_object(3.0)
32.748 μs (38 allocations: 1.69 KiB)
2-element Array{String,1}:
"Something"
"Some number"The reflection can be done at compile-time using @confcall_fast:
julia> @confcall_fast function describe_object end
describe_object (generic function with 1 method)
julia> @btime describe_object(3.0)
7.377 ns (1 allocation: 32 bytes)
("Something", "Some number")but it involves generated functions, so it revises poorly (as of Julia 1.4). Adding/removing methods will not work after the first call.