Erlang：简单重构 [英] Erlang: simple refactoring

问题描述

考虑代码：

f(command1, UserId) ->
    case is_registered(UserId) of
        true ->
            %% do command1
            ok;
        false ->
            not_registered
    end;

f(command2, UserId) ->
    case is_registered(UserId) of
        true ->
            %% do command2
            ok;
        false ->
            not_registered
    end.

is_registered(UserId) ->
    %% some checks

现在想象有很多命令，他们都是首先致电 is_registered 。
有没有办法推广这个行为（重构这个代码）？我的意思是在所有命令中放置相同的案例并不是个好主意。

Now imagine that there are a lot of commands and they are all call is_registered at first. Is there any way to generalize this behavior (refactor this code)? I mean that it's not a good idea to place the same case in all the commands.

推荐答案

我会与

f(Command, UserId) ->
    case is_registered(UserId) of
         true  ->
             run_command(Command);
         false ->
             not_registered
    end.


run_command(command1) -> ok;   % do command1
run_command(command2) -> ok.   % do command2

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