erlang 中 include 和include_lib

code path:
the code path consists of the current working directory and all Erlang object 
code directories under the library directory $OTPROOT/lib, where $OTPROOT 
is the installation directory of Erlang/OTP, code:root_dir(). 

code:lib_dir/1:
这个函数主要用于查找库目录的路径，例如一个名为 Name 且放在 $OTPROOT/lib 目录下的应用的根目录，
或是引自于 ERL_LIBS 环境变量下的一个目录。
If there is a regular directory called Name or Name-Vsn in the code path with
 an ebin subdirectory, the path to this directory is returned (not the ebin directory). 

所以:原来写的
-include("../client_dev/include/client_dev.hrl").是错的,应该是
-include("./deps/client_dev/include/client_dev.hrl").还是错的:
通过code:lib_dir/1 的解释:
实际上:
 code:lib_dir(client_dev).结果是:
"/home/dev/Work/cheetah/wxclient/deps/client_dev"

就要该成:
-include_lib("client_dev/include/client_dev.hrl").

-include("wxclient.hrl"). 这个 wxclient.hrl 是在 include/ 下面的
是在编译的时候包含进去, 这个配置在
rebar.config 的 erl_opt 的 -i 参数, 相当于erlc

---可以通过-include和-include_lib来包含文件，两者的区别是include-lib不能通过绝对路径查找文件，
而是在你当前Erlang的lib目录进行查找。摘自 http://www.cnblogs.com/samis/archive/2011/05/03/2034957.html

down vote
I think you can use:

-include_lib("snmp/include/snmp_types.hrl").
include_lib is similar to include, but should not point out an absolute file. Instead, the first path component (possibly after variable substitution) is assumed to be the name of an application.

Example:
-include_lib("kernel/include/file.hrl").
The code server uses code:lib_dir(kernel) to find the directory of the current (latest) version of Kernel, and then the subdirectory
include is searched for the file file.hrl.
<./pre>