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from dataclasses import dataclass
from mypy.nodes import (
AssignmentStmt,
CallExpr,
Expression,
FuncDef,
MemberExpr,
NameExpr,
ReturnStmt,
Statement,
)
from refurb.checks.common import ReadCountVisitor, check_block_like
from refurb.error import Error
from refurb.visitor import TraverserVisitor
@dataclass
class ErrorInfo(Error):
r"""
When an API has a Fluent Interface (the ability to chain multiple calls together), you should
chain those calls instead of repeatedly assigning and using the value.
Sometimes a return statement can be written more succinctly:
Bad:
```python
def get_tensors(device: str) -> torch.Tensor:
t1 = torch.ones(2, 1)
t2 = t1.long()
t3 = t2.to(device)
return t3
def process(file_name: str):
common_columns = ["col1_renamed", "col2_renamed", "custom_col"]
df = spark.read.parquet(file_name)
df = df \
.withColumnRenamed('col1', 'col1_renamed') \
.withColumnRenamed('col2', 'col2_renamed')
df = df \
.select(common_columns) \
.withColumn('service_type', F.lit('green'))
return df
```
Good:
```python
def get_tensors(device: str) -> torch.Tensor:
t3 = (
torch.ones(2, 1)
.long()
.to(device)
)
return t3
def process(file_name: str):
common_columns = ["col1_renamed", "col2_renamed", "custom_col"]
df = (
spark.read.parquet(file_name)
.withColumnRenamed('col1', 'col1_renamed')
.withColumnRenamed('col2', 'col2_renamed')
.select(common_columns)
.withColumn('service_type', F.lit('green'))
)
return df
```
"""
name = "use-fluid-interface"
code = 184
categories = ("readability",)
def check(node: FuncDef, errors: list[Error]) -> None:
check_block_like(check_stmts, node.body, errors)
def check_call(node: Expression, name: str | None = None) -> bool:
match node:
# Single chain
case CallExpr(callee=MemberExpr(expr=NameExpr(name=x), name=_)):
if name is None or name == x:
# Exclude other references
x_expr = NameExpr(x)
x_expr.fullname = x
visitor = ReadCountVisitor(x_expr)
visitor.accept(node)
return visitor.read_count == 1
return False
# Nested
case CallExpr(callee=MemberExpr(expr=call_node, name=_)):
return check_call(call_node, name=name)
return False
class NameReferenceVisitor(TraverserVisitor):
name: NameExpr
referenced: bool
def __init__(self, name: NameExpr, stmt: Statement | None = None) -> None:
super().__init__()
self.name = name
self.stmt = stmt
self.referenced = False
def visit_name_expr(self, node: NameExpr) -> None:
if not self.referenced and node.fullname == self.name.fullname:
self.referenced = True
def check_stmts(stmts: list[Statement], errors: list[Error]) -> None:
last = ""
visitors: list[NameReferenceVisitor] = []
for stmt in stmts:
for visitor in visitors:
visitor.accept(stmt)
# No need to track referenced variables anymore
visitors = [visitor for visitor in visitors if not visitor.referenced]
match stmt:
case AssignmentStmt(lvalues=[NameExpr(name=name)], rvalue=rvalue):
if last and check_call(rvalue, name=last):
if f"{last}'" == name:
errors.append(
ErrorInfo.from_node(
stmt,
"Assignment statement should be chained",
)
)
else:
# We need to ensure that the variable is not referenced somewhere else
name_expr = NameExpr(name=last)
name_expr.fullname = last
visitors.append(NameReferenceVisitor(name_expr, stmt))
last = name if name != "_" else ""
case ReturnStmt(expr=rvalue):
if last and rvalue is not None and check_call(rvalue, name=last):
errors.append(
ErrorInfo.from_node(
stmt,
"Return statement should be chained",
)
)
case _:
last = ""
# Ensure that variables are not referenced
errors.extend(
[
ErrorInfo.from_node(
visitor.stmt,
"Assignment statement should be chained",
)
for visitor in visitors
if not visitor.referenced and visitor.stmt is not None
]
)
|
