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Trivial dataclass cleanups: #6218

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Merged
ericvsmith merged 1 commit into from
Mar 24, 2018
Merged

Trivial dataclass cleanups: #6218

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49 changes: 26 additions & 23 deletions Lib/dataclasses.py
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import sys
import copy
import types
from copy import deepcopy
import inspect

__all__ = ['dataclass',
Expand Down Expand Up @@ -137,7 +137,7 @@
# For boxes that are blank, __hash__ is untouched and therefore
# inherited from the base class. If the base is object, then
# id-based hashing is used.
# Note that a class may have already __hash__=None if it specified an
# Note that a class may already have __hash__=None if it specified an
# __eq__ method in the class body (not one that was created by
# @dataclass).
# See _hash_action (below) for a coded version of this table.
Expand All @@ -147,7 +147,7 @@
class FrozenInstanceError(AttributeError): pass

# A sentinel object for default values to signal that a
# default-factory will be used.
# default factory will be used.
# This is given a nice repr() which will appear in the function
# signature of dataclasses' constructors.
class _HAS_DEFAULT_FACTORY_CLASS:
Expand Down Expand Up @@ -249,6 +249,7 @@ class _DataclassParams:
'unsafe_hash',
'frozen',
)

def __init__(self, init, repr, eq, order, unsafe_hash, frozen):
self.init = init
self.repr = repr
Expand All @@ -267,6 +268,7 @@ def __repr__(self):
f'frozen={self.frozen}'
')')


# This function is used instead of exposing Field creation directly,
# so that a type checker can be told (via overloads) that this is a
# function whose type depends on its parameters.
Expand Down Expand Up @@ -307,6 +309,8 @@ def _tuple_str(obj_name, fields):
def _create_fn(name, args, body, *, globals=None, locals=None,
return_type=MISSING):
# Note that we mutate locals when exec() is called. Caller beware!
# The only callers are internal to this module, so no worries
# about external callers.
if locals is None:
locals = {}
return_annotation = ''
Expand Down Expand Up @@ -429,26 +433,25 @@ def _init_fn(fields, frozen, has_post_init, self_name):

body_lines = []
for f in fields:
# Do not initialize the pseudo-fields, only the real ones.
line = _field_init(f, frozen, globals, self_name)
if line is not None:
# line is None means that this field doesn't require
# initialization. Just skip it.
# line is None means that this field doesn't require
# initialization (it's a pseudo-field). Just skip it.
if line:
body_lines.append(line)

# Does this class have a post-init function?
if has_post_init:
params_str = ','.join(f.name for f in fields
if f._field_type is _FIELD_INITVAR)
body_lines += [f'{self_name}.{_POST_INIT_NAME}({params_str})']
body_lines.append(f'{self_name}.{_POST_INIT_NAME}({params_str})')

# If no body lines, use 'pass'.
if not body_lines:
body_lines = ['pass']

locals = {f'_type_{f.name}': f.type for f in fields}
return _create_fn('__init__',
[self_name] +[_init_param(f) for f in fields if f.init],
[self_name] + [_init_param(f) for f in fields if f.init],
body_lines,
locals=locals,
globals=globals,
Expand All @@ -457,7 +460,7 @@ def _init_fn(fields, frozen, has_post_init, self_name):

def _repr_fn(fields):
return _create_fn('__repr__',
['self'],
('self',),
['return self.__class__.__qualname__ + f"(' +
', '.join([f"{f.name}={{self.{f.name}!r}}"
for f in fields]) +
Expand Down Expand Up @@ -496,7 +499,7 @@ def _cmp_fn(name, op, self_tuple, other_tuple):
# '(other.x,other.y)'.

return _create_fn(name,
['self', 'other'],
('self', 'other'),
[ 'if other.__class__ is self.__class__:',
f' return {self_tuple}{op}{other_tuple}',
'return NotImplemented'])
Expand All @@ -505,12 +508,12 @@ def _cmp_fn(name, op, self_tuple, other_tuple):
def _hash_fn(fields):
self_tuple = _tuple_str('self', fields)
return _create_fn('__hash__',
['self'],
('self',),
[f'return hash({self_tuple})'])


def _get_field(cls, a_name, a_type):
# Return a Field object, for this field name and type. ClassVars
# Return a Field object for this field name and type. ClassVars
# and InitVars are also returned, but marked as such (see
# f._field_type).

Expand Down Expand Up @@ -560,9 +563,9 @@ def _get_field(cls, a_name, a_type):
raise TypeError(f'field {f.name} cannot have a '
'default factory')
# Should I check for other field settings? default_factory
# seems the most serious to check for. Maybe add others. For
# example, how about init=False (or really,
# init=<not-the-default-init-value>)? It makes no sense for
# seems the most serious to check for. Maybe add others.
# For example, how about init=False (or really,
# init=<not-the-default-init-value>)? It makes no sense for
# ClassVar and InitVar to specify init=<anything>.

# For real fields, disallow mutable defaults for known types.
Expand Down Expand Up @@ -903,7 +906,7 @@ def _asdict_inner(obj, dict_factory):
return type(obj)((_asdict_inner(k, dict_factory), _asdict_inner(v, dict_factory))
for k, v in obj.items())
else:
return deepcopy(obj)
return copy.deepcopy(obj)


def astuple(obj, *, tuple_factory=tuple):
Expand Down Expand Up @@ -943,7 +946,7 @@ def _astuple_inner(obj, tuple_factory):
return type(obj)((_astuple_inner(k, tuple_factory), _astuple_inner(v, tuple_factory))
for k, v in obj.items())
else:
return deepcopy(obj)
return copy.deepcopy(obj)


def make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True,
Expand Down Expand Up @@ -1032,9 +1035,9 @@ class C:
if f.name not in changes:
changes[f.name] = getattr(obj, f.name)

# Create the new object, which calls __init__() and __post_init__
# (if defined), using all of the init fields we've added and/or
# left in 'changes'.
# If there are values supplied in changes that aren't fields, this
# will correctly raise a TypeError.
# Create the new object, which calls __init__() and
# __post_init__() (if defined), using all of the init fields
# we've added and/or left in 'changes'. If there are values
# supplied in changes that aren't fields, this will correctly
# raise a TypeError.
return obj.__class__(**changes)