Hands-On Design Patterns and Best Practices with Julia

Using the SimpleTraits.jl package

The SimpleTraits.jl package (https://github.com/mauro3/SimpleTraits.jl) may be used to make programming traits a little easier.

Let's try to redo the LiquidityStyle example using SimpleTraits. First, define a trait called IsLiquid, as follows:

@traitdef IsLiquid{T}

The syntax may look a little awkward since the T seems to be doing nothing, but it is actually required because the trait is applicable for a specific type T. The next thing is to assign types to this trait:

@traitimpl IsLiquid{Cash}@traitimpl IsLiquid{Investment}

Then, a special syntax with four colons can be used to define functions that take objects exhibiting the trait:

@traitfn marketprice(x::::IsLiquid) = error("Please implement pricing ...