Hands-On Design Patterns and Best Practices with Julia

Implementing trait behavior

Now that we can tell which types are liquid and which are not, we can define methods that take objects with those traits. First, let's do something really simple:

# The thing is tradable if it is liquidtradable(x::T) where {T} = tradable(LiquidityStyle(T), x)tradable(::IsLiquid, x) = truetradable(::IsIlliquid, x) = false

In Julia, types are first-class citizens. The tradable(x::T) where {T} signature captures the type of argument as T. Since we have already defined the LiquidityStyle function, we can derive whether the passed argument exhibits the IsLiquid or IsIlliquid trait. So, the first tradable method simply takes the return value of LiquidityStyle(T) and passes it as the first argument for the other two ...