Erlang：将记录传递给函数？

Question

以下代码在编译时会发出警告：

23> c(passing_records).                                              
passing_records.erl:8: Warning: wrong number of arguments in format call
{ok,passing_records}

但是当我尝试运行它时，尝试将变量传递给名为 的记录时出现此错误pass：

22> passing_records:record_passing([#pass{arg1=2,name="x",to_go=5}]).
* 1: record pass undefined

代码如下：

-module(passing_records).
-export([record_passing/1]).
-record(pass, {arg1 ,
                name="",
                to_go=0}).  

record_passing( #pass{arg1 = ARG1, name = NAME, to_go = TO_GO}) ->
        io:format("~p ~p~n", [ARG1,NAME,TO_GO]).    

Answer 1

record pass undefined报错的原因是需要用rr命令在shell中加载记录才能直接使用。有关更多信息，请参阅此问题。

当我这样做时，我遇到了编译器警告的问题：

Eshell V5.9  (abort with ^G)
1> c("/tmp/passing_records", [{outdir, "/tmp/"}]).
c("/tmp/passing_records", [{outdir, "/tmp/"}]).
/tmp/passing_records.erl:8: Warning: wrong number of arguments in format call
{ok,passing_records}
2> rr(passing_records).
[pass]
3> passing_records:record_passing([#pass{arg1=2,name="x",to_go=5}]).
** exception error: no function clause matching 
                    passing_records:record_passing([#pass{
                                                     arg1 = 2,name = "x",
                                                     to_go = 5}]) (/tmp/passing_records.erl, line 7)
4> passing_records:record_passing(#pass{arg1=2,name="x",to_go=5}).
** exception error: bad argument
     in function  io:format/3
        called as io:format(<0.24.0>,"~p ~p~n",[2,"x",5])

（您还在列表中传递记录，而该函数只需要一条记录；因此第 3 行出现错误。）