Stop checking minimum name length by default

doc/data/messages/i/invalid-name/details.rst

@@ -80,7 +80,7 @@ Pylint provides predefined naming patterns for some names. These patterns are of
 based on a Naming Style but there is no option to choose one of the styles mentioned above.
 The pattern can be overwritten with the options discussed below.
 
-The following type of names are checked with a predefined pattern:
+The following types of names are checked with a predefined pattern:
 
 +--------------------+-------------------------------------------------------+------------------------------------------------------------+
 | Name type          | Good names                                            | Bad names                                                  |
@@ -95,6 +95,13 @@ The following type of names are checked with a predefined pattern:
 |                    |  ``TopName`` is allowed but ``TTopName`` isn't.       |                                                            |
 +--------------------+-------------------------------------------------------+------------------------------------------------------------+
 
+Before pylint 3.0, most predefined patterns also enforced a minimum length
+of three characters. If this behavior is desired in versions 3.0 and following,
+it can be had by providing custom regular expressions as described next. (Or,
+if the ``disallowed-name`` check is sufficient instead of ``invalid-name``,
+providing the single option ``bad-names-rgxs="^..?$"`` will suffice to fail 1-2
+character names.
+
 Custom regular expressions
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 

doc/whatsnew/fragments/2018.user_action

@@ -0,0 +1,20 @@
+The ``invalid-name`` message no longer checks for a minimum length of 3 characters by default.
+(This was an unadvertised commingling of concerns between casing
+and name length, and users regularly reported this to be surprising.)
+
+If checking for a minimum length is still desired, it can be regained in two ways:
+
+- If you are content with a ``disallowed-name`` message (instead of ``invalid-name``),
+then simply add the option ``bad-names-rgxs="^..?$"``, which will fail 1-2
+character-long names. (Ensure you enable ``disallowed-name``.)
+
+- If you would prefer an ``invalid-name`` message to be emitted, or would prefer
+finer-grained control over the circumstances in which messages are emitted
+(classes vs. methods, etc.), then avail yourself of the regex options described
+`here <https://pylint.readthedocs.io/en/stable/user_guide/configuration/all-options.html#main-checker>`_.
+(In particular, take note of the commented out options in the "example configuration" given at
+the bottom of the section.) The prior regexes can be found in the
+`pull request <https://github.com/pylint-dev/pylint/pull/8813>`_
+that removed the length requirements.
+
+Closes #2018

pylint/checkers/base/name_checker/naming_style.py

@@ -47,47 +47,47 @@ def get_regex(cls, name_type: str) -> Pattern[str]:
 class SnakeCaseStyle(NamingStyle):
     """Regex rules for snake_case naming style."""
 
-    CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]+$")
+    CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$")
     MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\WA-Z]*$")
     CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]*|__.*__)$")
     COMP_VAR_RGX = CLASS_NAME_RGX
     DEFAULT_NAME_RGX = re.compile(
-        r"([^\W\dA-Z][^\WA-Z]{2,}|_[^\WA-Z]*|__[^\WA-Z\d_][^\WA-Z]+__)$"
+        r"([^\W\dA-Z][^\WA-Z]*|_[^\WA-Z]*|__[^\WA-Z\d_][^\WA-Z]+__)$"
     )
-    CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]{2,}|__.*__)$")
+    CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\WA-Z]*|__.*__)$")
 
 
 class CamelCaseStyle(NamingStyle):
     """Regex rules for camelCase naming style."""
 
-    CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]+$")
+    CLASS_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$")
     MOD_NAME_RGX = re.compile(r"[^\W\dA-Z][^\W_]*$")
     CONST_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]*|__.*__)$")
     COMP_VAR_RGX = MOD_NAME_RGX
-    DEFAULT_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$")
-    CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\W_]{2,}|__.*__)$")
+    DEFAULT_NAME_RGX = re.compile(r"([^\W\dA-Z][^\W_]*|__[^\W\dA-Z_]\w+__)$")
+    CLASS_ATTRIBUTE_RGX = re.compile(r"([^\W\dA-Z][^\W_]*|__.*__)$")
 
 
 class PascalCaseStyle(NamingStyle):
     """Regex rules for PascalCase naming style."""
 
-    CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]+$")
+    CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\W_]*$")
     MOD_NAME_RGX = CLASS_NAME_RGX
     CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]*|__.*__)$")
     COMP_VAR_RGX = CLASS_NAME_RGX
-    DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]{2,}|__[^\W\dA-Z_]\w+__)$")
-    CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\W_]{2,}$")
+    DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\W_]*|__[^\W\dA-Z_]\w+__)$")
+    CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\W_]*$")
 
 
 class UpperCaseStyle(NamingStyle):
     """Regex rules for UPPER_CASE naming style."""
 
-    CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]+$")
+    CLASS_NAME_RGX = re.compile(r"[^\W\da-z][^\Wa-z]*$")
     MOD_NAME_RGX = CLASS_NAME_RGX
     CONST_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]*|__.*__)$")
     COMP_VAR_RGX = CLASS_NAME_RGX
-    DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]{2,}|__[^\W\dA-Z_]\w+__)$")
-    CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\Wa-z]{2,}$")
+    DEFAULT_NAME_RGX = re.compile(r"([^\W\da-z][^\Wa-z]*|__[^\W\dA-Z_]\w+__)$")
+    CLASS_ATTRIBUTE_RGX = re.compile(r"[^\W\da-z][^\Wa-z]*$")
 
 
 class AnyStyle(NamingStyle):

tests/functional/d/disable_msg_next_line.py

@@ -12,7 +12,7 @@ def function_B(arg1, arg2):
 
 # pylint: disable-next=invalid-name, f-string-without-interpolation
 def function_C():
-    x = "string"  # [unused-variable, invalid-name]
+    X = "string"  # [unused-variable, invalid-name]
     return f"This should be a normal string"  # [f-string-without-interpolation]
 
 

tests/functional/d/disable_msg_next_line.txt

@@ -1,5 +1,5 @@
-invalid-name:15:4:15:5:function_C:"Variable name ""x"" doesn't conform to snake_case naming style":HIGH
-unused-variable:15:4:15:5:function_C:Unused variable 'x':UNDEFINED
+invalid-name:15:4:15:5:function_C:"Variable name ""X"" doesn't conform to snake_case naming style":HIGH
+unused-variable:15:4:15:5:function_C:Unused variable 'X':UNDEFINED
 f-string-without-interpolation:16:11:16:44:function_C:Using an f-string that does not have any interpolated variables:UNDEFINED
 invalid-name:19:0:19:14:function_D:"Function name ""function_D"" doesn't conform to snake_case naming style":HIGH
 unused-argument:19:21:19:25:function_D:Unused argument 'arg2':HIGH

tests/functional/i/invalid/invalid_name.py

@@ -29,8 +29,12 @@ def test():
         re = None
     return re
 
-def a(): # [invalid-name]
-    """yo"""
+def a():
+    """We no longer fail 1-character names by default."""
+
+
+def A():  # [invalid-name]
+    """But we do check casing."""
 
 
 def _generate_cmdline_tests():

tests/functional/i/invalid/invalid_name.txt

@@ -1,8 +1,8 @@
 invalid-name:12:0:12:3::"Constant name ""aaa"" doesn't conform to UPPER_CASE naming style":HIGH
 invalid-name:16:4:16:8::"Constant name ""time"" doesn't conform to UPPER_CASE naming style":HIGH
-invalid-name:32:0:32:5:a:"Function name ""a"" doesn't conform to snake_case naming style":HIGH
-invalid-name:46:4:46:13::"Constant name ""Foocapfor"" doesn't conform to UPPER_CASE naming style":HIGH
-invalid-name:62:0:62:68:a_very_very_very_long_function_name_WithCamelCase_to_make_it_sad:"Function name ""a_very_very_very_long_function_name_WithCamelCase_to_make_it_sad"" doesn't conform to snake_case naming style":HIGH
-invalid-name:70:23:70:29:FooBar.__init__:"Argument name ""fooBar"" doesn't conform to snake_case naming style":HIGH
-invalid-name:76:8:76:14:FooBar.func1:"Argument name ""fooBar"" doesn't conform to snake_case naming style":HIGH
-invalid-name:96:8:96:15:FooBar.test_disable_mixed:"Argument name ""fooBar2"" doesn't conform to snake_case naming style":HIGH
+invalid-name:36:0:36:5:A:"Function name ""A"" doesn't conform to snake_case naming style":HIGH
+invalid-name:50:4:50:13::"Constant name ""Foocapfor"" doesn't conform to UPPER_CASE naming style":HIGH
+invalid-name:66:0:66:68:a_very_very_very_long_function_name_WithCamelCase_to_make_it_sad:"Function name ""a_very_very_very_long_function_name_WithCamelCase_to_make_it_sad"" doesn't conform to snake_case naming style":HIGH
+invalid-name:74:23:74:29:FooBar.__init__:"Argument name ""fooBar"" doesn't conform to snake_case naming style":HIGH
+invalid-name:80:8:80:14:FooBar.func1:"Argument name ""fooBar"" doesn't conform to snake_case naming style":HIGH
+invalid-name:100:8:100:15:FooBar.test_disable_mixed:"Argument name ""fooBar2"" doesn't conform to snake_case naming style":HIGH

tests/functional/i/invalid/invalid_name/invalid_name_property.py

@@ -6,8 +6,8 @@
 import abc
 
 
-def custom_prop(f): # [invalid-name]
-    return property(f)
+def custom_prop(F): # [invalid-name]
+    return property(F)
 
 
 class FooClass:

tests/functional/i/invalid/invalid_name/invalid_name_property.txt

@@ -1,3 +1,3 @@
-invalid-name:9:16:9:17:custom_prop:"Argument name ""f"" doesn't conform to snake_case naming style":HIGH
+invalid-name:9:16:9:17:custom_prop:"Argument name ""F"" doesn't conform to snake_case naming style":HIGH
 invalid-name:21:4:21:11:FooClass.bar:"Attribute name ""bar"" doesn't conform to '[A-Z]+' pattern":INFERENCE
 invalid-name:37:4:37:11:AnotherFooClass.foo:"Attribute name ""foo"" doesn't conform to '[A-Z]+' pattern":INFERENCE

tests/functional/n/name/name_preset_snake_case.txt

@@ -1,5 +1,5 @@
 invalid-name:6:0:6:13::"Constant name ""SOME_CONSTANT"" doesn't conform to snake_case naming style ('([^\\W\\dA-Z][^\\WA-Z]*|__.*__)$' pattern)":HIGH
-invalid-name:13:0:13:13:MyClass:"Class name ""MyClass"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]+$' pattern)":HIGH
-invalid-name:25:0:25:12:sayHello:"Function name ""sayHello"" doesn't conform to snake_case naming style ('([^\\W\\dA-Z][^\\WA-Z]{2,}|_[^\\WA-Z]*|__[^\\WA-Z\\d_][^\\WA-Z]+__)$' pattern)":HIGH
-invalid-name:29:0:29:13:FooEnum:"Class name ""FooEnum"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]+$' pattern)":HIGH
-invalid-name:34:0:34:9:Bar:"Class name ""Bar"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]+$' pattern)":HIGH
+invalid-name:13:0:13:13:MyClass:"Class name ""MyClass"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]*$' pattern)":HIGH
+invalid-name:25:0:25:12:sayHello:"Function name ""sayHello"" doesn't conform to snake_case naming style ('([^\\W\\dA-Z][^\\WA-Z]*|_[^\\WA-Z]*|__[^\\WA-Z\\d_][^\\WA-Z]+__)$' pattern)":HIGH
+invalid-name:29:0:29:13:FooEnum:"Class name ""FooEnum"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]*$' pattern)":HIGH
+invalid-name:34:0:34:9:Bar:"Class name ""Bar"" doesn't conform to snake_case naming style ('[^\\W\\dA-Z][^\\WA-Z]*$' pattern)":HIGH

tests/functional/n/namePresetCamelCase.txt

@@ -1,3 +1,3 @@
 invalid-name:3:0:3:13::"Constant name ""SOME_CONSTANT"" doesn't conform to camelCase naming style ('([^\\W\\dA-Z][^\\W_]*|__.*__)$' pattern)":HIGH
-invalid-name:10:0:10:13:MyClass:"Class name ""MyClass"" doesn't conform to camelCase naming style ('[^\\W\\dA-Z][^\\W_]+$' pattern)":HIGH
-invalid-name:22:0:22:13:say_hello:"Function name ""say_hello"" doesn't conform to camelCase naming style ('([^\\W\\dA-Z][^\\W_]{2,}|__[^\\W\\dA-Z_]\\w+__)$' pattern)":HIGH
+invalid-name:10:0:10:13:MyClass:"Class name ""MyClass"" doesn't conform to camelCase naming style ('[^\\W\\dA-Z][^\\W_]*$' pattern)":HIGH
+invalid-name:22:0:22:13:say_hello:"Function name ""say_hello"" doesn't conform to camelCase naming style ('([^\\W\\dA-Z][^\\W_]*|__[^\\W\\dA-Z_]\\w+__)$' pattern)":HIGH