How to determine if Julia object is callable

Question

In Julia, what's the best way to determine whether an object is callable? (E.g. is there an analog of python's callable function?)

EDIT: Here's what one could wish for:

f() = println("Hi")
x = [1,2,3]
a = 'A'

callable(f)    # => true
callable(x)    # => false
callable(a)    # => false
callable(sin)  # => true

Answer 1

iscallable(f) = !isempty(methods(f))

This is the method used in Base (see here).

But consider rethinking your problem. Custom dispatch like this will probably be slow.

Answer 2

How about this:

julia> function iscallable(f)
       try
           f()
           return true

       catch MethodError
           return false
       end
end
iscallable (generic function with 1 method)


julia> f() = 3
f (generic function with 1 method)

julia> iscallable(f)
true

julia> x = [1,2]
2-element Array{Int64,1}:
 1
 2

julia> iscallable(x)
false

This is actually quite a Pythonic thing to do (and I suspect not very efficient). What's the use case?