8000 Implement new NamedTuple syntax (#2245) · python/mypy@ec5c476 · GitHub
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Implement new NamedTuple syntax (#2245)
Starting from Python 3.6b1, typing.NamedTuple supports the PEP 526 syntax: from typing import NamedTuple class Employee(NamedTuple): name: str salary: int manager = Employee('John Doe', 9000) Here is the support of this feature for mypy. It works only with --fast-parser, since it is required to parse PEP 526 syntax. Roughly half of the tests are simply adapted from tests for function NamedTuple syntax, plus another half are specific for the new syntax.
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‎mypy/semanal.py

Lines changed: 54 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -53,7 +53,7 @@
5353
ImportFrom, ImportAll, Block, LDEF, NameExpr, MemberExpr,
5454
IndexExpr, TupleExpr, ListExpr, ExpressionStmt, ReturnStmt,
5555
RaiseStmt, AssertStmt, OperatorAssignmentStmt, WhileStmt,
56-
ForStmt, BreakStmt, ContinueStmt, IfStmt, TryStmt, WithStmt, DelStmt,
56+
ForStmt, BreakStmt, ContinueStmt, IfStmt, TryStmt, WithStmt, DelStmt, PassStmt,
5757
GlobalDecl, SuperExpr, DictExpr, CallExpr, RefExpr, OpExpr, UnaryExpr,
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SliceExpr, CastExpr, RevealTypeExpr, TypeApplication, Context, SymbolTable,
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SymbolTableNode, BOUND_TVAR, UNBOUND_TVAR, ListComprehension, GeneratorExpr,
@@ -63,7 +63,7 @@
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YieldFromExpr, NamedTupleExpr, TypedDictExpr, NonlocalDecl, SymbolNode,
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SetComprehension, DictionaryComprehension, TYPE_ALIAS, TypeAliasExpr,
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YieldExpr, ExecStmt, Argument, BackquoteExpr, ImportBase, AwaitExpr,
66-
IntExpr, FloatExpr, UnicodeExpr, EllipsisExpr,
66+
IntExpr, FloatExpr, UnicodeExpr, EllipsisExpr, TempNode,
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COVARIANT, CONTRAVARIANT, INVARIANT, UNBOUND_IMPORTED, LITERAL_YES,
6868
)
6969
from mypy.visitor import NodeVisitor
@@ -547,6 +547,8 @@ def check_function_signature(self, fdef: FuncItem) -> None:
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548548
def visit_class_def(self, defn: ClassDef) -> None:
549549
self.clean_up_bases_and_infer_type_variables(defn)
550+
if self.analyze_namedtuple_classdef(defn):
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return
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self.setup_class_def_analysis(defn)
551553

552554
self.bind_class_type_vars(defn)
@@ -713,6 +715,56 @@ def analyze_unbound_tvar(self, t: Type) -> Tuple[str, TypeVarExpr]:
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return unbound.name, cast(TypeVarExpr, sym.node)
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return None
715717

718+
def analyze_namedtuple_classdef(self, defn: ClassDef) -> bool:
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# special case for NamedTuple
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for base_expr in defn.base_type_exprs:
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if isinstance(base_expr, RefExpr):
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base_expr.accept(self)
723+
if base_expr.fullname == 'typing.NamedTuple':
724+
node = self.lookup(defn.name, defn)
725+
if node is not None:
726+
node.kind = GDEF # TODO in process_namedtuple_definition also applies here
727+
items, types = self.check_namedtuple_classdef(defn)
728+
node.node = self.build_namedtuple_typeinfo(defn.name, items, types)
729+
return True
730+
return False
731+
732+
def check_namedtuple_classdef(self, defn: ClassDef) -> Tuple[List[str], List[Type]]:
733+
NAMEDTUP_CLASS_ERROR = ('Invalid statement in NamedTuple definition; '
734+
'expected "field_name: field_type"')
735+
if self.options.python_version < (3, 6):
736+
self.fail('NamedTuple class syntax is only supported in Python 3.6', defn)
737+
return [], []
738+
if len(defn.base_type_exprs) > 1:
739+
self.fail('NamedTuple should be a single base', defn)
740+
items = [] # type: List[str]
741+
types = [] # type: List[Type]
742+
for stmt in defn.defs.body:
743+
if< 8000 /span> not isinstance(stmt, AssignmentStmt):
744+
# Still allow pass or ... (for empty namedtuples).
745+
if (not isinstance(stmt, PassStmt) and
746+
not (isinstance(stmt, ExpressionStmt) and
747+
isinstance(stmt.expr, EllipsisExpr))):
748+
self.fail(NAMEDTUP_CLASS_ERROR, stmt)
749+
elif len(stmt.lvalues) > 1 or not isinstance(stmt.lvalues[0], NameExpr):
750+
# An assignment, but an invalid one.
751+
self.fail(NAMEDTUP_CLASS_ERROR, stmt)
752+
else:
753+
# Append name and type in this case...
754+
name = stmt.lvalues[0].name
755+
items.append(name)
756+
types.append(AnyType() if stmt.type is None else self.anal_type(stmt.type))
757+
# ...despite possible minor failures that allow further analyzis.
758+
if name.startswith('_'):
759+
self.fail('NamedTuple field name cannot start with an underscore: {}'
760+
.format(name), stmt)
761+
if stmt.type is None or hasattr(stmt, 'new_syntax') and not stmt.new_syntax:
762+
self.fail(NAMEDTUP_CLASS_ERROR, stmt)
763+
elif not isinstance(stmt.rvalue, TempNode):
764+
# x: int assigns rvalue to TempNode(AnyType())
765+
self.fail('Right hand side values are not supported in NamedTuple', stmt)
766+
return items, types
767+
716768
def setup_class_def_analysis(self, defn: ClassDef) -> None:
717769
"""Prepare for the analysis of a class definition."""
718770
if not defn.info:

‎mypy/test/testcheck.py

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -66,6 +66,7 @@
6666
'check-warnings.test',
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'check-async-await.test',
6868
'check-newtype.test',
69+
'check-class-namedtuple.test',
6970
'check-columns.test',
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]
7172

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