Warning: behaviour my_behaviour undefined

在make:all()时出现Warning: behaviour my_behaviour undefined这样的警告，回头检查了一遍代码，没发现有什么问题；代码完全是按照教程来的，不可能出错。

上网查，也没找到解决方法。没办法，只能看源码啦。

查找路径: make:all/0 --> make:all/1 --> make:do_make_files/2 --> make:process/3 --> make:recompilep/4 --> make:recompile/4 --> compile:file/2 --> compile:do_compile/2 --> compile:internal/2 --> compile:passes/2 --> compile:passes_1/1 --> compile:standard_passes/0 --> compile:lint_module/1 --> erl_lint:module/3 --> erl_lint:forms/2 --> erl_lint:post_traversal_check/2 --> erl_lint:check_behaviour/1 --> erl_lint:behaviour_check/2 --> erl_lint:all_behaviour_callbacks/3 --> erl_lint:behaviour_callbacks/3

即:

behaviour_callbacks(Line, B, St0) ->

    try B:behaviour_info(callbacks) of

        Funcs when is_list(Funcs) ->

            All = all(fun({FuncName, Arity}) ->

                              is_atom(FuncName) andalso is_integer(Arity);

                             ({FuncName, Arity, Spec}) ->

                                  is_atom(FuncName) andalso is_integer(Arity)

                                       andalso is_list(Spec);

                         (_Other) ->

                              false

                      end,

                      Funcs),

             MaybeRemoveSpec = fun({_F,_A}=FA) -> FA;

                                      ({F,A,_S}) -> {F,A};

                                      (Other) -> Other

                                  end,

            if

                All =:= true ->

                    {[MaybeRemoveSpec(F) || F <- Funcs], St0};

                true ->

                    St1 = add_warning(Line,

                                      {ill_defined_behaviour_callbacks,B},

                                      St0),

                    {[], St1}

            end;

        undefined ->

            St1 = add_warning(Line, {undefined_behaviour_callbacks,B}, St0),

            {[], St1};

        _Other ->

            St1 = add_warning(Line, {ill_defined_behaviour_callbacks,B}, St0),

            {[], St1}

    catch

        _:_ ->

            St1 = add_warning(Line, {undefined_behaviour,B}, St0),

            {[], St1}

end.

假如make的时候在搜索路径找不到行为定义模块(即my_behaviour模块), 那么try B:behaviour_info(callbacks) of 这一句会抛出异常，也就加入undefined_behaviour的警告，最后在erl_lint:format_error/1中会打印这个警告:

format_error({undefined_behaviour,Behaviour}) ->

io_lib:format("behaviour ~w undefined", [Behaviour]);

 

知道了原因，解决办法就不难得出了。

可以在make:all().之前先加一些搜索路径， 使用code:add_patha/1 或者erl –pa ./ebin –eval “make:all()”.

 

还有一种情况是:

behaviour使用模块在behaviour定义模块之前编译时，B:behaviour_info(callbacks)这一句也会抛出异常，同样会产生behaviour xxx undefined的警告。

这时就需要确保behaviour定义模块在behaviour使用模块编译之前编译，暂时想到两种方法：一是先编译behaviour定义模块，将其产生的beam文件放到ebin目录下，然后再make:all(); 二是: 修改Emakefile文件，定义多个规则以实现先编译behaviour定义模块。