Add singleton escape hatch to B008 documentation (#8501)

## Summary: Closes: #8378.
astral-sh · Nov 7, 2023 · c3d6d5d · c3d6d5d
1 parent 9a8400a
commit c3d6d5d
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Showing 3 changed files with 23 additions and 13 deletions.
diff --git a/crates/ruff_linter/src/rules/flake8_bugbear/rules/function_call_in_argument_default.rs b/crates/ruff_linter/src/rules/flake8_bugbear/rules/function_call_in_argument_default.rs
@@ -50,6 +50,16 @@ use crate::checkers::ast::Checker;
 ///     return arg
 /// ```
 ///
+/// If the use of a singleton is intentional, assign the result call to a
+/// module-level variable, and use that variable in the default argument:
+/// ```python
+/// ERROR = ValueError("Hosts weren't successfully added")
+///
+///
+/// def add_host(error: Exception = ERROR) -> None:
+///     ...
+/// ```
+///
 /// ## Options
 /// - `flake8-bugbear.extend-immutable-calls`
 #[violation]
@@ -62,9 +72,9 @@ impl Violation for FunctionCallInDefaultArgument {
     fn message(&self) -> String {
         let FunctionCallInDefaultArgument { name } = self;
         if let Some(name) = name {
-            format!("Do not perform function call `{name}` in argument defaults")
+            format!("Do not perform function call `{name}` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable")
         } else {
-            format!("Do not perform function call in argument defaults")
+            format!("Do not perform function call in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable")
         }
     }
 }

diff --git a/...lake8_bugbear/snapshots/ruff_linter__rules__flake8_bugbear__tests__B008_B006_B008.py.snap b/...lake8_bugbear/snapshots/ruff_linter__rules__flake8_bugbear__tests__B008_B006_B008.py.snap
@@ -1,29 +1,29 @@
 ---
 source: crates/ruff_linter/src/rules/flake8_bugbear/mod.rs
 ---
-B006_B008.py:102:61: B008 Do not perform function call `range` in argument defaults
+B006_B008.py:102:61: B008 Do not perform function call `range` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 101 | # N.B. we're also flagging the function call in the comprehension
 102 | def list_comprehension_also_not_okay(default=[i**2 for i in range(3)]):
     |                                                             ^^^^^^^^ B008
 103 |     pass
     |
 
-B006_B008.py:106:64: B008 Do not perform function call `range` in argument defaults
+B006_B008.py:106:64: B008 Do not perform function call `range` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 106 | def dict_comprehension_also_not_okay(default={i: i**2 for i in range(3)}):
     |                                                                ^^^^^^^^ B008
 107 |     pass
     |
 
-B006_B008.py:110:60: B008 Do not perform function call `range` in argument defaults
+B006_B008.py:110:60: B008 Do not perform function call `range` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 110 | def set_comprehension_also_not_okay(default={i**2 for i in range(3)}):
     |                                                            ^^^^^^^^ B008
 111 |     pass
     |
 
-B006_B008.py:126:39: B008 Do not perform function call `time.time` in argument defaults
+B006_B008.py:126:39: B008 Do not perform function call `time.time` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 124 | # B008
 125 | # Flag function calls as default args (including if they are part of a sub-expression)
@@ -32,21 +32,21 @@ B006_B008.py:126:39: B008 Do not perform function call `time.time` in argument d
 127 |     ...
     |
 
-B006_B008.py:130:12: B008 Do not perform function call `dt.datetime.now` in argument defaults
+B006_B008.py:130:12: B008 Do not perform function call `dt.datetime.now` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 130 | def f(when=dt.datetime.now() + dt.timedelta(days=7)):
     |            ^^^^^^^^^^^^^^^^^ B008
 131 |     pass
     |
 
-B006_B008.py:134:30: B008 Do not perform function call in argument defaults
+B006_B008.py:134:30: B008 Do not perform function call in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 134 | def can_even_catch_lambdas(a=(lambda x: x)()):
     |                              ^^^^^^^^^^^^^^^ B008
 135 |     ...
     |
 
-B006_B008.py:239:31: B008 Do not perform function call `dt.datetime.now` in argument defaults
+B006_B008.py:239:31: B008 Do not perform function call `dt.datetime.now` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 237 | # B006 and B008
 238 | # We should handle arbitrary nesting of these B008.
@@ -55,7 +55,7 @@ B006_B008.py:239:31: B008 Do not perform function call `dt.datetime.now` in argu
 240 |     pass
     |
 
-B006_B008.py:245:22: B008 Do not perform function call `map` in argument defaults
+B006_B008.py:245:22: B008 Do not perform function call `map` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 243 | # Don't flag nested B006 since we can't guarantee that
 244 | # it isn't made mutable by the outer operation.
@@ -64,15 +64,15 @@ B006_B008.py:245:22: B008 Do not perform function call `map` in argument default
 246 |     pass
     |
 
-B006_B008.py:250:19: B008 Do not perform function call `random.randint` in argument defaults
+B006_B008.py:250:19: B008 Do not perform function call `random.randint` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 249 | # B008-ception.
 250 | def nested_b008(a=random.randint(0, dt.datetime.now().year)):
     |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ B008
 251 |     pass
     |
 
-B006_B008.py:250:37: B008 Do not perform function call `dt.datetime.now` in argument defaults
+B006_B008.py:250:37: B008 Do not perform function call `dt.datetime.now` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
     |
 249 | # B008-ception.
 250 | def nested_b008(a=random.randint(0, dt.datetime.now().year)):

diff --git a/...pshots/ruff_linter__rules__flake8_bugbear__tests__extend_immutable_calls_arg_default.snap b/...pshots/ruff_linter__rules__flake8_bugbear__tests__extend_immutable_calls_arg_default.snap
@@ -1,7 +1,7 @@
 ---
 source: crates/ruff_linter/src/rules/flake8_bugbear/mod.rs
 ---
-B008_extended.py:24:51: B008 Do not perform function call `Depends` in argument defaults
+B008_extended.py:24:51: B008 Do not perform function call `Depends` in argument defaults; instead, perform the call within the function, or read the default from a module-level singleton variable
    |
 24 | def error_due_to_missing_import(data: List[str] = Depends(None)):
    |                                                   ^^^^^^^^^^^^^ B008