Make the message less prescriptive as the import need to be taken into account

Author: Pierre-Sassoulas

doc/data/messages/c/consider-math-not-float/bad.py

@@ -0,0 +1 @@
+swag = float("inf")  # [consider-math-not-float]

doc/data/messages/c/consider-math-not-float/details.rst

@@ -0,0 +1,40 @@
+This is an extension check because the typing advantage could be fixed.
+
+Regarding performance, float("nan") and float("inf") are slower than their counterpart math.inf and math.nan by a factor of 4 after the initial import of math.
+
+.. code-block:: python
+
+    import math
+    import timeit
+
+    time_math_inf = timeit.timeit('math.nan', globals=globals(), number=10**8)
+    print(f'math.nan: {time_math_inf:.2f} seconds')
+
+    import timeit
+    time_inf_str = timeit.timeit('float("nan")', number=10**8)
+    print(f'float("nan"): {time_inf_str:.2f} seconds')
+
+Result::
+
+    math.nan: 1.24 seconds
+    float("nan"): 5.15 seconds
+
+But if we take the initial import into account it's worse.
+
+.. code-block:: python
+
+    import timeit
+
+    time_math_inf = timeit.timeit('import math;math.nan', globals=globals(), number=10**8)
+    print(f'math.nan: {time_math_inf:.2f} seconds')
+
+    import timeit
+    time_inf_str = timeit.timeit('float("nan")', number=10**8)
+    print(f'float("nan"): {time_inf_str:.2f} seconds')
+
+Result::
+
+    math.nan: 9.08 seconds
+    float("nan"): 5.33 seconds
+
+So the decision depends on how and how often you need to use it and what matter to you.

doc/data/messages/u/use-math-not-float/good.py renamed to doc/data/messages/c/consider-math-not-float/good.py

@@ -88,9 +88,10 @@ Code Style checker Messages
   'typing.NamedTuple' uses the well-known 'class' keyword with type-hints for
   readability (it's also faster as it avoids an internal exec call). Disabled
   by default!
-:use-math-not-float (R6106): *%smath.%s is preferable to %s*
+:consider-math-not-float (R6106): *Consider %smath.%s instead of %s*
   Using math.inf or math.nan permits to benefit from typing and it is 4 time
-  faster than a float call (notwithstanding the initial import of math).
+  faster than a float call (after the initial import of math). This check also
+  catch typo in float calls as a side effect.
 
 
 .. _pylint.extensions.comparison_placement:

doc/data/messages/u/use-math-not-float/pylintrc renamed to doc/data/messages/c/consider-math-not-float/pylintrc

@@ -491,6 +491,7 @@ All messages in the refactor category:
    refactor/condition-evals-to-constant
    refactor/confusing-consecutive-elif
    refactor/consider-alternative-union-syntax
+   refactor/consider-math-not-float
    refactor/consider-merging-isinstance
    refactor/consider-refactoring-into-while-condition
    refactor/consider-swap-variables
@@ -559,7 +560,6 @@ All messages in the refactor category:
    refactor/use-a-generator
    refactor/use-dict-literal
    refactor/use-list-literal
-   refactor/use-math-not-float
    refactor/use-set-for-membership
    refactor/use-yield-from
    refactor/useless-object-inheritance

doc/data/messages/u/use-math-not-float/bad.py

@@ -1,4 +1,4 @@
-Add a ``use-math-not-float`` message. ``float("nan")`` and ``float("inf")`` are slower
+Add a ``consider-math-not-float`` message. ``float("nan")`` and ``float("inf")`` are slower
 than their counterpart ``math.inf`` and ``math.nan`` by a factor of 4 (notwithstanding
 the initial import of math) and they are also not well typed when using mypy.
 

doc/user_guide/checkers/extensions.rst

@@ -76,11 +76,11 @@ class CodeStyleChecker(BaseChecker):
             },
         ),
         "R6106": (
-            "%smath.%s is preferable to %s",
-            "use-math-not-float",
-            "Using math.inf or math.nan permits to benefit from typing "
-            "and it is 4 time faster than a float call (notwithstanding"
-            " the initial import of math).",
+            "Consider %smath.%s instead of %s",
+            "consider-math-not-float",
+            "Using math.inf or math.nan permits to benefit from typing and it is 4 "
+            "time faster than a float call (after the initial import of math). "
+            "This check also catch typo in float calls as a side effect.",
         ),
     }
     options = (
@@ -109,7 +109,7 @@ def open(self) -> None:
             or self.linter.config.max_line_length
         )
 
-    @only_required_for_messages("prefer-typing-namedtuple", "use-math-not-float")
+    @only_required_for_messages("prefer-typing-namedtuple", "consider-math-not-float")
     def visit_call(self, node: nodes.Call) -> None:
         if self._py36_plus:
             called = safe_infer(node.func)
@@ -140,7 +140,7 @@ def visit_call(self, node: nodes.Call) -> None:
                         )[0]
                     minus = "-" if math_call == "inf" and value.startswith("-") else ""
                     self.add_message(
-                        "use-math-not-float",
+                        "consider-math-not-float",
                         node=node,
                         args=(minus, math_call, node.as_string()),
                         confidence=INFERENCE,

doc/user_guide/messages/messages_overview.rst

@@ -1,18 +1,18 @@
-"""Functional test for use-math-not-float."""
+"""Functional test for consider-math-not-float."""
 
-inf_float = float("inf")  # [use-math-not-float]
-neg_inf_float = float('-inf')  # [use-math-not-float]
-pos_inf_float = float("+inf")  # [use-math-not-float]
-infinity_float = float("infinity")  # [use-math-not-float]
-neg_infinity_float = float("-infinity")  # [use-math-not-float]
+inf_float = float("inf")  # [consider-math-not-float]
+neg_inf_float = float('-inf')  # [consider-math-not-float]
+pos_inf_float = float("+inf")  # [consider-math-not-float]
+infinity_float = float("infinity")  # [consider-math-not-float]
+neg_infinity_float = float("-infinity")  # [consider-math-not-float]
 large_exp_float = float("1e1000")
 neg_large_exp_float = float("-1e1000")
 very_large_exp_float = float("2.5E9999")
-invalid_inf_float = float("in")  # [use-math-not-float]
-invalid_float_call = float("in", base=10)  # [use-math-not-float]
-nan_float = float("nan")  # [use-math-not-float]
-neg_nan_float = float("-nan")  # [use-math-not-float]
-pos_nan_float = float("+nan")  # [use-math-not-float]
-upper_nan_float = float("NaN")  # [use-math-not-float]
-typo_nan_float = float("nani")  # [use-math-not-float]
-other_typo_nan_float = float("nna")  # [use-math-not-float]
+invalid_inf_float = float("in")  # [consider-math-not-float]
+invalid_float_call = float("in", base=10)  # [consider-math-not-float]
+nan_float = float("nan")  # [consider-math-not-float]
+neg_nan_float = float("-nan")  # [consider-math-not-float]
+pos_nan_float = float("+nan")  # [consider-math-not-float]
+upper_nan_float = float("NaN")  # [consider-math-not-float]
+typo_nan_float = float("nani")  # [consider-math-not-float]
+other_typo_nan_float = float("nna")  # [consider-math-not-float]