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Issue detect useless generator pattern #520

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Issue detect useless generator pattern #520

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1f4af99
use len(node.keywords) by num_keyword_args in condition l.76
Karine-Bauch Jul 19, 2023
b0f2085
Issue #503 - add rule for useless generator pattern
Karine-Bauch Jul 21, 2023
b97b726
Issue #503 - change rule for useless generator pattern
Karine-Bauch Jul 27, 2023
c12724e
Issue #503 - change rule for useless generator pattern
Karine-Bauch Jul 30, 2023
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2 changes: 2 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -5,3 +5,5 @@
/.tox
/build/
/dist/
venv
```
18 changes: 17 additions & 1 deletion src/flake8_comprehensions/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ def __init__(self, tree: ast.AST) -> None:
"C419 Unnecessary list comprehension passed to {func}() prevents "
+ "short-circuiting - rewrite as a generator."
),
"C420": "C420 Unnecessary generator - remove it or rewrite with as iterator",
}

def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
Expand Down Expand Up @@ -73,7 +74,7 @@ def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
elif (
num_positional_args == 1
and node.func.id == "dict"
and len(node.keywords) == 0
and num_keyword_args == 0
and isinstance(node.args[0], (ast.GeneratorExp, ast.ListComp))
and isinstance(node.args[0].elt, ast.Tuple)
and len(node.args[0].elt.elts) == 2
Expand Down Expand Up @@ -199,6 +200,21 @@ def run(self) -> Generator[tuple[int, int, str, type[Any]], None, None]:
type(self),
)

elif (
node.func.id == "sorted"
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From the original issue:

the (a for a in b) generator construct doesn't seem particularly useful and just adds an unnecessary context switch of the generator.

I think we can check every generator, not only those inside sorted call.
This mean that the check would be only the isinstance of node as ast.GeneratorExp and isinstance of node.elt as ast.Name. What do you think?

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You should be right.
We should verify if the Generator do something, in all cases, not only for sorted call.
I need to put this on my desktop : KISS 👍

and num_positional_args > 0
and (
isinstance(node.args[0], ast.GeneratorExp)
and isinstance(node.args[0].elt, ast.Name)
)
):
yield (
node.lineno,
node.col_offset,
self.messages["C420"],
type(self),
)

elif (
node.func.id in {"list", "reversed"}
and num_positional_args > 0
Expand Down