Merge pull request #7 from inaka/elbrujohalcon.7.suggestion__use_macr…

…os_appropr

Suggestion: Use Macros appropriately

README.md

@@ -32,6 +32,7 @@ Table of Contents:
  * [Strings](#strings)
  * [IOLists over string concatenation](#iolists-over-string-concatenation)
  * [Macros](#macros)
+ * [No Macros](#no-macros)
  * [Uppercase Macros](#uppercase-macros)
  * [No module or function name macros](#no-module-or-function-name-macros)
  * [Misc](#misc)
@@ -235,6 +236,16 @@ Erlang syntax is horrible amirite? So you might as well make the best of it, rig
 
 ### Macros
 
+***
+##### No Macros
+> Don't use macros, except for very specific cases, that include
+> * Predefined ones: ``?MODULE``, ``?MODULE_STRING`` and ``?LINE``
+> * Magic numbers: ``?DEFAULT_TIMEOUT``
+
+*Examples*: [macros](src/macros.erl)
+
+*Reasoning*: Macros make code harder to debug. If you're trying to use them to avoid repeating the same block of code over and over, you can use functions for that.
+
 ***
 ##### Uppercase macros
 > Macros should be named in ALL_UPPER_CASE:

src/macro_names.erl

@@ -1,9 +1,9 @@
 -module(macro_names).
 
--define(bad, bad).
--define(BADMACRONAME, bad).
--define(Bad_Macro_Name, bad).
--define(Bad_L33t_M@Cr0, bad).
+-define(bad, 1).
+-define(BADMACRONAME, 2).
+-define(Bad_Macro_Name, 3).
+-define(Bad_L33t_M@Cr0, 4).
 
--define(GOOD, good).
--define(GOOD_MACRO_NAME, good).
+-define(GOOD, 5).
+-define(GOOD_MACRO_NAME, 6).

src/macros.erl

@@ -0,0 +1,32 @@
+-module(macros).
+
+-define(OTHER_MODULE, other_module).
+-define(LOG_ERROR(Error),
+ error_logger:error_msg(
+ "~p:~p >> Error: ~p~n\tStack: ~p",
+ [?MODULE, ?LINE, Error, erlang:get_stacktrace()])).
+
+-define(HTTP_CREATED, 201).
+
+-export([bad/0, good/0]).
+
+bad() ->
+ try
+ ?OTHER_MODULE:some_function(that, may, fail, 201)
+ catch
+ _:Error ->
+ ?LOG_ERROR(Error)
+ end.
+
+good() ->
+ try
+ other_module:some_function(that, may, fail, ?HTTP_CREATED)
+ catch
+ _:Error ->
+ log_error(?LINE, Error)
+ end.
+
+log_error(Line, Error) ->
+ error_logger:error_msg(
+ "~p:~p >> Error: ~p~n\tStack: ~p",
+ [?MODULE, Line, Error, erlang:get_stacktrace()]).