Provide some hints for the bad-builtin message. Closes issue #522.

5 files changed, 20 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index acf1e83..4c0d67a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -55,6 +55,8 @@ ChangeLog for Pylint
     * Don't emit redefined-outer-name for __future__ directives.
       Closes issue #520.
 
+    * Provide some hints for the bad-builtin message. Closes issue #522.
+
 
 2015-03-14 -- 1.4.3
 
diff --git a/pylint/checkers/base.py b/pylint/checkers/base.py
index d50369c..532ad01 100644
--- a/pylint/checkers/base.py
+++ b/pylint/checkers/base.py
@@ -69,6 +69,12 @@ BAD_FUNCTIONS = ['map', 'filter']
 if sys.version_info < (3, 0):
     BAD_FUNCTIONS.append('input')
 
+# Some hints regarding the use of bad builtins.
+BUILTIN_HINTS = {
+    'map': 'Using a list comprehension can be clearer.',
+}
+BUILTIN_HINTS['filter'] = BUILTIN_HINTS['map']
+
 # Name categories that are always consistent with all naming conventions.
 EXEMPT_NAME_CATEGORIES = set(('exempt', 'ignore'))
 
@@ -493,7 +499,7 @@ functions, methods
                   'usage. Consider using `ast.literal_eval` for safely evaluating '
                   'strings containing Python expressions '
                   'from untrusted sources. '),
-        'W0141': ('Used builtin function %r',
+        'W0141': ('Used builtin function %s',
                   'bad-builtin',
                   'Used when a black listed builtin function is used (see the '
                   'bad-function option). Usual black listed functions are the ones '
@@ -777,7 +783,12 @@ functions, methods
                 elif name == 'eval':
                     self.add_message('eval-used', node=node)
                 if name in self.config.bad_functions:
-                    self.add_message('bad-builtin', node=node, args=name)
+                    hint = BUILTIN_HINTS.get(name)
+                    if hint:
+                        args = "%r. %s" % (name, hint)
+                    else:
+                        args = repr(name)
+                    self.add_message('bad-builtin', node=node, args=args)
 
     @check_messages('assert-on-tuple')
     def visit_assert(self, node):
diff --git a/pylint/test/functional/bad_builtin.py b/pylint/test/functional/bad_builtin.py
index fd4eaf6..1ca9790 100644
--- a/pylint/test/functional/bad_builtin.py
+++ b/pylint/test/functional/bad_builtin.py
@@ -1,3 +1,4 @@
 # pylint: disable=missing-docstring

 

 TEST = map(str, (1, 2, 3)) # [bad-builtin]

+TEST1 = filter(str, (1, 2, 3)) # [bad-builtin]

diff --git a/pylint/test/functional/bad_builtin.txt b/pylint/test/functional/bad_builtin.txt
index 8a3d610..552f196 100644
--- a/pylint/test/functional/bad_builtin.txt
+++ b/pylint/test/functional/bad_builtin.txt
@@ -1 +1,2 @@
-bad-builtin:3::Used builtin function 'map'
+bad-builtin:3::Used builtin function 'map'. Using a list comprehension can be clearer.
+bad-builtin:4::Used builtin function 'filter'. Using a list comprehension can be clearer.
diff --git a/pylint/test/messages/func_3k_removed_stuff_py_30.txt b/pylint/test/messages/func_3k_removed_stuff_py_30.txt
index e7ede06..a8e462e 100644
--- a/pylint/test/messages/func_3k_removed_stuff_py_30.txt
+++ b/pylint/test/messages/func_3k_removed_stuff_py_30.txt
@@ -1,5 +1,5 @@
 E: 12:function: Instance of 'unicode' has no 'looower' member
-W:  3: Used builtin function 'filter'
-W:  3: Used builtin function 'map'
+W:  3: Used builtin function 'filter'. Using a list comprehension can be clearer.
+W:  3: Used builtin function 'map'. Using a list comprehension can be clearer.
 W:  4: __future__ import is not the first non docstring statement
 W:  6: Relative import 'func_w0302', should be 'input.func_w0302'