CODEWITHSUNDEEP
erlang
Bocco
Bocco

Reputation: 23

Avoiding duplication of code in a "receive" when an input changes the type of messages being received

I want to be able to write a function which when its input is in some invalid state (let's say it's an integer, and invalid means -1), it receives messages with any kind of information, but when its input is valid, it only receives messages of the same kind as its input. As an example, this is what a possible solution might look like:

f(-1) ->
    receive
        ...
        {a, AnyInput} ->
            % Do something
        ...
    end

f(ValidInput) ->
    receive
        ...
        {a, ValidInput} ->
            % Do something
        ...
    end

The main concern here is duplicating code, as the receive contains a large amount of, otherwise, identical code (there are also many other messages types in the same receive).

Is there any coding pattern which could help me here?

I also have the freedom to set the invalid state as any value, including undef, if that would help.

Upvotes: 2

Views: 50

Answers (1)

Greg
Greg

Reputation: 8340

f(Input) ->
    receive
        ...
        {a, AnyInput} when Input =:= -1 ->
            % Do something
        ...
        {a, Input} ->
            % Do something
        ...
    end

Upvotes: 2

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