erlang本身提供一个接口,可以用来检查模块是否有导出函数,这个接口是erlang:function_exported/3,但是很多时候这个接口无法正常使用。 下面重现一下这个问题: 1> erlang:function_exported(crypto,start,0). false 2> crypto:start(). ok 3> erlang:function_exported(crypto,start,0). true 注意:例子中并不是说一...
1 function_exported(Module,Function,Arity) -> boolean() 检测模块 Module 是否已经加载并且是否包含一个输出的函数 Function/Arity,如果是,则返回 true,否则返回 false。任何的 BIF(用 C 实现而不是 Erlang 实现的函数) 都返回 false。 1 erlang:function_exported(lists, dropwhile, 2). ...
这个接口是用来检查模块函数是否导出,但是,如果模块没加载过,这个函数返回值就是false 3> erlang:function_exported(odbc,start,0). false 4> odbc:start(). ok 5> erlang:function_exported(odbc,start,0). true 我之前也讨论过这个问题,解决方案看这里 erlang:list_to_binary() 如果参数是多层嵌套结构,就会...
A concept to understand is that Erlang has bothlocalandexternalcalls. Local calls are those function calls you can make with functions that might not be exported. They're just of the formatAtom(Args). An external call, on the other hand, can only be done with exported functions and has th...
erlang:function_exported(Module, Function, Arity) -> boolean() Module = module() Function = atom() Arity = arity() Returns true if the module Module is loaded and contains an exported function Function/Arity, or if there is a BIF (a built-in function implemented in C) with the specifie...
case erlang:function_exported(Module, test, 0) of true -> io:format(" - Calling ~p:test() ...", [Module]), case catch Module:test() of ok -> io:format(" ok.~n"), reload; Reason -> io:format(" fail: ~p.~n", [Reason]), ...
case erlang:function_exported(Module, test, 0) of true -> io:format(" - Calling ~p:test() ...", [Module]), case catch Module:test() of ok -> io:format(" ok.~n"), reload; Reason -> io:format(" fail: ~p.~n", [Reason]), ...
erlang:function_exported/3检测一个函数是否输出并被加载 erlang:garbage_collect/0对当前进程进行垃圾回收操作 erlang:garbage_collect/1对指定进程进行垃圾回收操作 erlang:get/0返回进程里的所有字典值 erlang:get/1从进程字典里获取一个值 erlang:get_cookie/0获取本地节点的魔饼值(magic cookie) erlang:get_keys...
Module = Function = atom() Args = [term()]Returns the result of applying Function in Module to Args. The applied function must be exported from Module. The arity of the function is the length of Args. > apply(lists, reverse, [[a, b, c]]). [c,b,a] apply can be used to ...
运用内置函数spawn(Module,Exported_Function,list of Arguments) 新建进程示例: 新建文件tut14.erl,代码如下: -module(tut14).-export([start/0,say_something/2]).%实现重复打印输入的内容,次数可配say_something(What,0)->done;say_something(What,Times)->io:format("~p~n",[What]),say_something(What...