Priority in dispatch

General Usage
1

I have a famility of functions

b(t, x::T) =

called in a loop

for i in 1:n 
   t = t + dt
   x = x + dt*f(t, x)
end

It turns out that sometimes I’d need the index i as well and I’d like to define

f((i,s)::Tuple, x) = f(s, x)
for i in 1:n 
   t = t + dt
   x = x + dt*f((i,s), x)
end

Which creates ambiguity between all my f(s, x::T) and f((i,s)::Tuple, x). Of course I could
play with the order of the arguments or use a different function name but just to be sure: is there a way do define

f((i,s)::Tuple, x) = f(s, x)

such it has higher priority than (say)

f(s, x::Float64)

but less than f((i,s)::Tuple, x::Float64)?

3

Instead of doing dispatch, can’t you just use a branch?

function f(s, x)
    s isa Tuple && return _f(s[2], x)
    return _f(s, x)
end

_f(s, x::Float64)  = ...
1 Like
4

Or using dispatch:

f((i,s)::Tuple, x) = f(s,x)
f(s,x) = _f(s,x)
_f(s, x::Float64)  = ...
_f(s, ...) = ...
1 Like