IsDef.jl
This package provides primitives for dispatching on whether certain methods are implemented or not.
For installation or usage, open julia repl and run
using IsDef
which gives you access to following functions
-
isdef(f, arg1, arg2)::Bool
/isdef(f, Arg1Type, Arg2Type)::Bool
checks whether a function is defined for the given types.If at least one of the arguments is not a type, all arguments are automatically converted to types for you.
-
Out(f, arg1, arg2)::ReturnType
/Out(f, Arg1Type, Arg2Type)::ReturnType
returns the returntype of the given functioncall.Note, that
Out
may return an abstract type that is wider than necessary, like e.g.Any
. If a functioncall is not defined, or predictably throws an error,IsDef.NotApplicable
is returned.Out
is internally used byisdef
.
Internally of Out(f, Arg1Type, Arg2Type)
a one-argument-version of Out
is used which expects a single Tuple type, specifying the entire call signature. This is the heart of the IsDef
package. For the example it would be
Out(Tuple{typeof(f), Arg1Type, Arg2Type})
If you want to specify inference of your method (output of Out
), or whether it is defined (output of isdef
), you need to overload this very one-argument method of Out
. For the example it could be
Out(::Type{<:Tuple{typeof(f), Arg1Type, Arg2Type, Vararg}}) = ReturnType
Enjoy maintainable type inference.