mypy.renaming.VariableRenameVisitor

class documentation

class VariableRenameVisitor(TraverserVisitor): (source)

Rename variables to allow redefinition of variables.

For example, consider this code:

x = 0 f(x)

x = "a" g(x)

It will be transformed like this:

x' = 0 f(x')

x = "a" g(x)

There will be two independent variables (x' and x) that will have separate inferred types. The publicly exposed variant will get the non-suffixed name. This is the last definition at module top level and the first definition (argument) within a function.

Renaming only happens for assignments within the same block. Renaming is performed before semantic analysis, immediately after parsing.

The implementation performs a rudimentary static analysis. The analysis is overly conservative to keep things simple.

Method	`__init__`	Undocumented
Method	`analyze_lvalue`	Process assignment; in particular, keep track of (re)defined names.
Method	`clear`	Undocumented
Method	`current_block`	Undocumented
Method	`enter_block`	Undocumented
Method	`enter_loop`	Undocumented
Method	`enter_scope`	Undocumented
Method	`enter_try`	Undocumented
Method	`flush_refs`	Rename all references within the current scope.
Method	`handle_arg`	Store function argument.
Method	`handle_def`	Store new name definition.
Method	`handle_ref`	Store reference to defined name.
Method	`handle_refine`	Store assignment to an existing name (that replaces previous value, if any).
Method	`is_nested`	Undocumented
Method	`record_assignment`	Record assignment to given name and return True if it defines a new variable.
Method	`reject_redefinition_of_vars_in_loop`	Reject redefinition of variables in the innermost loop.
Method	`reject_redefinition_of_vars_in_scope`	Make it impossible to redefine defined variables in the current scope.
Method	`rename_refs`	Undocumented
Method	`visit_assignment_stmt`	Undocumented
Method	`visit_block`	Undocumented
Method	`visit_break_stmt`	Undocumented
Method	`visit_class_def`	Undocumented
Method	`visit_continue_stmt`	Undocumented
Method	`visit_for_stmt`	Undocumented
Method	`visit_func_def`	Undocumented
Method	`visit_import`	Undocumented
Method	`visit_import_from`	Undocumented
Method	`visit_mypy_file`	Rename variables within a file.
Method	`visit_name_expr`	Undocumented
Method	`visit_try_stmt`	Undocumented
Method	`visit_while_stmt`	Undocumented
Method	`visit_with_stmt`	Undocumented
Instance Variable	`block_id`	Undocumented
Instance Variable	`block_loop_depth`	Undocumented
Instance Variable	`blocks`	Undocumented
Instance Variable	`disallow_redef_depth`	Undocumented
Instance Variable	`loop_depth`	Undocumented
Instance Variable	`num_reads`	Undocumented
Instance Variable	`refs`	Undocumented
Instance Variable	`scope_kinds`	Undocumented
Instance Variable	`var_blocks`	Undocumented

Inherited from TraverserVisitor:

Method	`visit_assert_stmt`	Undocumented
Method	`visit_assignment_expr`	Undocumented
Method	`visit_await_expr`	Undocumented
Method	`visit_backquote_expr`	Undocumented
Method	`visit_call_expr`	Undocumented
Method	`visit_cast_expr`	Undocumented
Method	`visit_comparison_expr`	Undocumented
Method	`visit_conditional_expr`	Undocumented
Method	`visit_decorator`	Undocumented
Method	`visit_del_stmt`	Undocumented
Method	`visit_dict_expr`	Undocumented
Method	`visit_dictionary_comprehension`	Undocumented
Method	`visit_exec_stmt`	Undocumented
Method	`visit_expression_stmt`	Undocumented
Method	`visit_func`	Undocumented
Method	`visit_generator_expr`	Undocumented
Method	`visit_if_stmt`	Undocumented
Method	`visit_index_expr`	Undocumented
Method	`visit_lambda_expr`	Undocumented
Method	`visit_list_comprehension`	Undocumented
Method	`visit_list_expr`	Undocumented
Method	`visit_member_expr`	Undocumented
Method	`visit_op_expr`	Undocumented
Method	`visit_operator_assignment_stmt`	Undocumented
Method	`visit_overloaded_func_def`	Undocumented
Method	`visit_print_stmt`	Undocumented
Method	`visit_raise_stmt`	Undocumented
Method	`visit_return_stmt`	Undocumented
Method	`visit_reveal_expr`	Undocumented
Method	`visit_set_comprehension`	Undocumented
Method	`visit_set_expr`	Undocumented
Method	`visit_slice_expr`	Undocumented
Method	`visit_star_expr`	Undocumented
Method	`visit_super_expr`	Undocumented
Method	`visit_tuple_expr`	Undocumented
Method	`visit_type_application`	Undocumented
Method	`visit_unary_expr`	Undocumented
Method	`visit_yield_expr`	Undocumented
Method	`visit_yield_from_expr`	Undocumented

def __init__(self): (source)

overrides mypy.traverser.TraverserVisitor.__init__

Undocumented

def analyze_lvalue(self, lvalue, is_nested=False): (source)

Process assignment; in particular, keep track of (re)defined names.

Args:

is_nested: True for non-outermost Lvalue in a multiple assignment such as: "x, y = ..."

Parameters
lvalue:`Lvalue`	Undocumented
is_nested:`bool`	Undocumented

def clear(self): (source)

Undocumented

def current_block(self): (source)

Undocumented

Returns
`int`	Undocumented

@contextmanager
def enter_block(self): (source)

Undocumented

Returns
`Iterator[None]`	Undocumented

@contextmanager
def enter_loop(self): (source)

Undocumented

Returns
`Iterator[None]`	Undocumented

@contextmanager
def enter_scope(self, kind): (source)

Undocumented

Parameters
kind:`int`	Undocumented
Returns
`Iterator[None]`	Undocumented

@contextmanager
def enter_try(self): (source)

Undocumented

Returns
`Iterator[None]`	Undocumented

def flush_refs(self): (source)

Rename all references within the current scope.

This will be called at the end of a scope.

def handle_arg(self, name): (source)

Store function argument.

Parameters
name:`str`	Undocumented

def handle_def(self, expr): (source)

Store new name definition.

Parameters
expr:`NameExpr`	Undocumented

def handle_ref(self, expr): (source)

Store reference to defined name.

Parameters
expr:`NameExpr`	Undocumented

def handle_refine(self, expr): (source)

Store assignment to an existing name (that replaces previous value, if any).

Parameters
expr:`NameExpr`	Undocumented

def is_nested(self): (source)

Undocumented

Returns
`int`	Undocumented

def record_assignment(self, name, can_be_redefined): (source)

Record assignment to given name and return True if it defines a new variable.

Args:

can_be_redefined: If True, allows assignment in the same block to redefine: this name (if this is a new definition)

Parameters
name:`str`	Undocumented
can_be_redefined:`bool`	Undocumented
Returns
`bool`	Undocumented

def reject_redefinition_of_vars_in_loop(self): (source)

Reject redefinition of variables in the innermost loop.

If there is an early exit from a loop, there may be ambiguity about which value may escape the loop. Example where this matters:

while f():

x = 0 if g():

break

x = '' # Error -- not a redefinition

reveal_type(x) # int

This method ensures that the second assignment to 'x' doesn't introduce a new variable.

def reject_redefinition_of_vars_in_scope(self): (source)

Make it impossible to redefine defined variables in the current scope.

This is used if we encounter a function definition that can make it ambiguous which definition is live. Example:

x = 0

def f() -> int:

return x

x = '' # Error -- cannot redefine x across function definition

def rename_refs(self, names, index): (source)

Undocumented

Parameters
names:`List[NameExpr]`	Undocumented
index:`int`	Undocumented

def visit_assignment_stmt(self, s): (source)

overrides mypy.traverser.TraverserVisitor.visit_assignment_stmt

Undocumented

Parameters
s:`AssignmentStmt`	Undocumented

def visit_block(self, block): (source)

overrides mypy.traverser.TraverserVisitor.visit_block

Undocumented

Parameters
block:`Block`	Undocumented

def visit_break_stmt(self, stmt): (source)

Undocumented

Parameters
stmt:`BreakStmt`	Undocumented

def visit_class_def(self, cdef): (source)

overrides mypy.traverser.TraverserVisitor.visit_class_def

Undocumented

Parameters
cdef:`ClassDef`	Undocumented

def visit_continue_stmt(self, stmt): (source)

Undocumented

Parameters
stmt:`ContinueStmt`	Undocumented

def visit_for_stmt(self, stmt): (source)

overrides mypy.traverser.TraverserVisitor.visit_for_stmt

Undocumented

Parameters
stmt:`ForStmt`	Undocumented

def visit_func_def(self, fdef): (source)

overrides mypy.traverser.TraverserVisitor.visit_func_def

Undocumented

Parameters
fdef:`FuncDef`	Undocumented

def visit_import(self, imp): (source)

overrides mypy.traverser.TraverserVisitor.visit_import

Undocumented

Parameters
imp:`Import`	Undocumented

def visit_import_from(self, imp): (source)

overrides mypy.traverser.TraverserVisitor.visit_import_from

Undocumented

Parameters
imp:`ImportFrom`	Undocumented

def visit_mypy_file(self, file_node): (source)

overrides mypy.traverser.TraverserVisitor.visit_mypy_file

Rename variables within a file.

This is the main entry point to this class.

Parameters
file_node:`MypyFile`	Undocumented

def visit_name_expr(self, expr): (source)

Undocumented

Parameters
expr:`NameExpr`	Undocumented

def visit_try_stmt(self, stmt): (source)

overrides mypy.traverser.TraverserVisitor.visit_try_stmt

Undocumented

Parameters
stmt:`TryStmt`	Undocumented

def visit_while_stmt(self, stmt): (source)

overrides mypy.traverser.TraverserVisitor.visit_while_stmt

Undocumented

Parameters
stmt:`WhileStmt`	Undocumented

def visit_with_stmt(self, stmt): (source)

overrides mypy.traverser.TraverserVisitor.visit_with_stmt

Undocumented

Parameters
stmt:`WithStmt`	Undocumented

block_id: int = (source)

Undocumented

block_loop_depth: Dict[int, int] = (source)

Undocumented

blocks: list = (source)

Undocumented

disallow_redef_depth: int = (source)

Undocumented

loop_depth: int = (source)

Undocumented

num_reads: List[Dict[str, int]] = (source)

Undocumented

refs: List[Dict[str, List[List[NameExpr]]]] = (source)

Undocumented

scope_kinds: List[int] = (source)

Undocumented

var_blocks: list = (source)

Undocumented