Please do you know how to setup the behaviors code?
CharlesO
D4no0
Nope, all you need is something like this:
defmodule ParseBehavior do
# Obviously replace any with your data types
@callback parse(data :: any) :: any
end
defmodule CustomerA do
@behaviour ParseBehavior
end
If you don’t implement the specified callbacks you will get a compilation warning.
You can also have the variant with the default implementation:
defmodule ParseBehavior do
@callback parse(data :: any) :: any
defmacro __using__(_opts) do
quote do
@behaviour ParseBehavior
def parse(data) do
# This will be the default implementation if not overriden
end
defoverridable parse: 1
end
end
end
defmodule CustomerA do
use ParseBehavior
# This definition will override the default definition
def parse(data) do
end
end
I wouldn’t recommend using the variant with default implementation unless that is strictly required, as it makes the code harder to read.
6
CharlesO
Please how do we get the return value from the customer module back to the behavior module?
For example, say CustomerA implements parse/1, how can that result be used in ParseBehavior module?
0
D4no0
You can’t, the module that defines behavior whole point is to make sure that you are implementing the required functions, it’s up to you how you call them afterwards.
You can either use the pattern you are already using with apply/3 or you can call directly the function, as module names are just plain atoms:
my_modules = [CustomerA, CustomerB]
for module <- my_modules do
module.parse(data)
end
You could add some compile-time checks to ensure that the module you are calling has the behavior declared, but I don’t see a lot of value from that.
1