erlang的abstract code

erlang的abstract code是编译的中间代码，很多工具如 erl_pp lint什么的都是根据这个做调整的。还有进一步的parse_transform也是基于它的。 所以，了解它非常重要。 erts user guide里面详细了描述了它的定义。我这里展示的是如何获取到某个模块的abstract code 以便进一步研究：

[root@localhost ~]# erl -s hello
Erlang R13B02 (erts-5.7.3) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false]

hello world
Eshell V5.7.3  (abort with ^G)
1>
BREAK: (a)bort (c)ontinue (p)roc info (i)nfo (l)oaded
       (v)ersion (k)ill (D)b-tables (d)istribution
[root@localhost ~]# cat hello.erl
-module(hello).
-export([start/0]).

start()->
    io:format("hello world~n",[]).
[root@localhost ~]# erlc +debug_info hello.erl
[root@localhost ~]# erl
Erlang R13B02 (erts-5.7.3) [source] [64-bit] [smp:2:2] [rq:2] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.7.3  (abort with ^G)
1> rp(beam_lib:chunks(hello, [abstract_code])).
{ok,{hello,[{abstract_code,{raw_abstract_v1,[{attribute,1,
                                                        file,
                                                        {"./hello.erl",1}},
                                             {attribute,1,module,hello},
                                             {attribute,2,export,[{start,0}]},
                                             {function,4,start,0,
                                                       [{clause,4,[],[],
                                                                [{call,5,
                                                                       {remote,5,{atom,5,io},{atom,5,format}},
                                                                       [{string,5,"hello world~n"},{nil,5}]}]}]},
                                             {eof,6}]}}]}}
ok
2>

对着文档开始好好分析吧。 Have fun!