diff options
| -rw-r--r-- | Lib/dataclasses.py | 326 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Core and Builtins/2023-10-14-00-05-17.gh-issue-109870.oKpJ3P.rst | 3 |
2 files changed, 185 insertions, 144 deletions
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py index 7db8a42..3acd03c 100644 --- a/Lib/dataclasses.py +++ b/Lib/dataclasses.py @@ -426,32 +426,95 @@ def _tuple_str(obj_name, fields): return f'({",".join([f"{obj_name}.{f.name}" for f in fields])},)' -def _create_fn(name, args, body, *, globals=None, locals=None, - return_type=MISSING): - # Note that we may mutate locals. Callers beware! - # The only callers are internal to this module, so no - # worries about external callers. - if locals is None: - locals = {} - return_annotation = '' - if return_type is not MISSING: - locals['__dataclass_return_type__'] = return_type - return_annotation = '->__dataclass_return_type__' - args = ','.join(args) - body = '\n'.join(f' {b}' for b in body) - - # Compute the text of the entire function. - txt = f' def {name}({args}){return_annotation}:\n{body}' - - # Free variables in exec are resolved in the global namespace. - # The global namespace we have is user-provided, so we can't modify it for - # our purposes. So we put the things we need into locals and introduce a - # scope to allow the function we're creating to close over them. - local_vars = ', '.join(locals.keys()) - txt = f"def __create_fn__({local_vars}):\n{txt}\n return {name}" - ns = {} - exec(txt, globals, ns) - return ns['__create_fn__'](**locals) +class _FuncBuilder: + def __init__(self, globals): + self.names = [] + self.src = [] + self.globals = globals + self.locals = {} + self.overwrite_errors = {} + self.unconditional_adds = {} + + def add_fn(self, name, args, body, *, locals=None, return_type=MISSING, + overwrite_error=False, unconditional_add=False, decorator=None): + if locals is not None: + self.locals.update(locals) + + # Keep track if this method is allowed to be overwritten if it already + # exists in the class. The error is method-specific, so keep it with + # the name. We'll use this when we generate all of the functions in + # the add_fns_to_class call. overwrite_error is either True, in which + # case we'll raise an error, or it's a string, in which case we'll + # raise an error and append this string. + if overwrite_error: + self.overwrite_errors[name] = overwrite_error + + # Should this function always overwrite anything that's already in the + # class? The default is to not overwrite a function that already + # exists. + if unconditional_add: + self.unconditional_adds[name] = True + + self.names.append(name) + + if return_type is not MISSING: + self.locals[f'__dataclass_{name}_return_type__'] = return_type + return_annotation = f'->__dataclass_{name}_return_type__' + else: + return_annotation = '' + args = ','.join(args) + body = '\n'.join(body) + + # Compute the text of the entire function, add it to the text we're generating. + self.src.append(f'{f' {decorator}\n' if decorator else ''} def {name}({args}){return_annotation}:\n{body}') + + def add_fns_to_class(self, cls): + # The source to all of the functions we're generating. + fns_src = '\n'.join(self.src) + + # The locals they use. + local_vars = ','.join(self.locals.keys()) + + # The names of all of the functions, used for the return value of the + # outer function. Need to handle the 0-tuple specially. + if len(self.names) == 0: + return_names = '()' + else: + return_names =f'({",".join(self.names)},)' + + # txt is the entire function we're going to execute, including the + # bodies of the functions we're defining. Here's a greatly simplified + # version: + # def __create_fn__(): + # def __init__(self, x, y): + # self.x = x + # self.y = y + # @recursive_repr + # def __repr__(self): + # return f"cls(x={self.x!r},y={self.y!r})" + # return __init__,__repr__ + + txt = f"def __create_fn__({local_vars}):\n{fns_src}\n return {return_names}" + ns = {} + exec(txt, self.globals, ns) + fns = ns['__create_fn__'](**self.locals) + + # Now that we've generated the functions, assign them into cls. + for name, fn in zip(self.names, fns): + fn.__qualname__ = f"{cls.__qualname__}.{fn.__name__}" + if self.unconditional_adds.get(name, False): + setattr(cls, name, fn) + else: + already_exists = _set_new_attribute(cls, name, fn) + + # See if it's an error to overwrite this particular function. + if already_exists and (msg_extra := self.overwrite_errors.get(name)): + error_msg = (f'Cannot overwrite attribute {fn.__name__} ' + f'in class {cls.__name__}') + if not msg_extra is True: + error_msg = f'{error_msg} {msg_extra}' + + raise TypeError(error_msg) def _field_assign(frozen, name, value, self_name): @@ -462,8 +525,8 @@ def _field_assign(frozen, name, value, self_name): # self_name is what "self" is called in this function: don't # hard-code "self", since that might be a field name. if frozen: - return f'__dataclass_builtins_object__.__setattr__({self_name},{name!r},{value})' - return f'{self_name}.{name}={value}' + return f' __dataclass_builtins_object__.__setattr__({self_name},{name!r},{value})' + return f' {self_name}.{name}={value}' def _field_init(f, frozen, globals, self_name, slots): @@ -546,7 +609,7 @@ def _init_param(f): def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init, - self_name, globals, slots): + self_name, func_builder, slots): # fields contains both real fields and InitVar pseudo-fields. # Make sure we don't have fields without defaults following fields @@ -565,11 +628,11 @@ def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init, raise TypeError(f'non-default argument {f.name!r} ' f'follows default argument {seen_default.name!r}') - locals = {f'__dataclass_type_{f.name}__': f.type for f in fields} - locals.update({ - '__dataclass_HAS_DEFAULT_FACTORY__': _HAS_DEFAULT_FACTORY, - '__dataclass_builtins_object__': object, - }) + locals = {**{f'__dataclass_type_{f.name}__': f.type for f in fields}, + **{'__dataclass_HAS_DEFAULT_FACTORY__': _HAS_DEFAULT_FACTORY, + '__dataclass_builtins_object__': object, + } + } body_lines = [] for f in fields: @@ -583,11 +646,11 @@ def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init, if has_post_init: params_str = ','.join(f.name for f in fields if f._field_type is _FIELD_INITVAR) - body_lines.append(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'] + body_lines = [' pass'] _init_params = [_init_param(f) for f in std_fields] if kw_only_fields: @@ -596,68 +659,34 @@ def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init, # (instead of just concatenting the lists together). _init_params += ['*'] _init_params += [_init_param(f) for f in kw_only_fields] - return _create_fn('__init__', - [self_name] + _init_params, - body_lines, - locals=locals, - globals=globals, - return_type=None) - - -def _repr_fn(fields, globals): - fn = _create_fn('__repr__', - ('self',), - ['return f"{self.__class__.__qualname__}(' + - ', '.join([f"{f.name}={{self.{f.name}!r}}" - for f in fields]) + - ')"'], - globals=globals) - return recursive_repr()(fn) - - -def _frozen_get_del_attr(cls, fields, globals): + func_builder.add_fn('__init__', + [self_name] + _init_params, + body_lines, + locals=locals, + return_type=None) + + +def _frozen_get_del_attr(cls, fields, func_builder): locals = {'cls': cls, 'FrozenInstanceError': FrozenInstanceError} condition = 'type(self) is cls' if fields: condition += ' or name in {' + ', '.join(repr(f.name) for f in fields) + '}' - return (_create_fn('__setattr__', - ('self', 'name', 'value'), - (f'if {condition}:', - ' raise FrozenInstanceError(f"cannot assign to field {name!r}")', - f'super(cls, self).__setattr__(name, value)'), - locals=locals, - globals=globals), - _create_fn('__delattr__', - ('self', 'name'), - (f'if {condition}:', - ' raise FrozenInstanceError(f"cannot delete field {name!r}")', - f'super(cls, self).__delattr__(name)'), - locals=locals, - globals=globals), - ) - - -def _cmp_fn(name, op, self_tuple, other_tuple, globals): - # Create a comparison function. If the fields in the object are - # named 'x' and 'y', then self_tuple is the string - # '(self.x,self.y)' and other_tuple is the string - # '(other.x,other.y)'. - - return _create_fn(name, - ('self', 'other'), - [ 'if other.__class__ is self.__class__:', - f' return {self_tuple}{op}{other_tuple}', - 'return NotImplemented'], - globals=globals) - -def _hash_fn(fields, globals): - self_tuple = _tuple_str('self', fields) - return _create_fn('__hash__', - ('self',), - [f'return hash({self_tuple})'], - globals=globals) + func_builder.add_fn('__setattr__', + ('self', 'name', 'value'), + (f' if {condition}:', + ' raise FrozenInstanceError(f"cannot assign to field {name!r}")', + f' super(cls, self).__setattr__(name, value)'), + locals=locals, + overwrite_error=True) + func_builder.add_fn('__delattr__', + ('self', 'name'), + (f' if {condition}:', + ' raise FrozenInstanceError(f"cannot delete field {name!r}")', + f' super(cls, self).__delattr__(name)'), + locals=locals, + overwrite_error=True) def _is_classvar(a_type, typing): @@ -834,19 +863,11 @@ def _get_field(cls, a_name, a_type, default_kw_only): return f -def _set_qualname(cls, value): - # Ensure that the functions returned from _create_fn uses the proper - # __qualname__ (the class they belong to). - if isinstance(value, FunctionType): - value.__qualname__ = f"{cls.__qualname__}.{value.__name__}" - return value - def _set_new_attribute(cls, name, value): # Never overwrites an existing attribute. Returns True if the # attribute already exists. if name in cls.__dict__: return True - _set_qualname(cls, value) setattr(cls, name, value) return False @@ -856,14 +877,22 @@ def _set_new_attribute(cls, name, value): # take. The common case is to do nothing, so instead of providing a # function that is a no-op, use None to signify that. -def _hash_set_none(cls, fields, globals): - return None +def _hash_set_none(cls, fields, func_builder): + # It's sort of a hack that I'm setting this here, instead of at + # func_builder.add_fns_to_class time, but since this is an exceptional case + # (it's not setting an attribute to a function, but to a scalar value), + # just do it directly here. I might come to regret this. + cls.__hash__ = None -def _hash_add(cls, fields, globals): +def _hash_add(cls, fields, func_builder): flds = [f for f in fields if (f.compare if f.hash is None else f.hash)] - return _set_qualname(cls, _hash_fn(flds, globals)) + self_tuple = _tuple_str('self', flds) + func_builder.add_fn('__hash__', + ('self',), + [f' return hash({self_tuple})'], + unconditional_add=True) -def _hash_exception(cls, fields, globals): +def _hash_exception(cls, fields, func_builder): # Raise an exception. raise TypeError(f'Cannot overwrite attribute __hash__ ' f'in class {cls.__name__}') @@ -1041,24 +1070,26 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, (std_init_fields, kw_only_init_fields) = _fields_in_init_order(all_init_fields) + func_builder = _FuncBuilder(globals) + if init: # Does this class have a post-init function? has_post_init = hasattr(cls, _POST_INIT_NAME) - _set_new_attribute(cls, '__init__', - _init_fn(all_init_fields, - std_init_fields, - kw_only_init_fields, - frozen, - has_post_init, - # The name to use for the "self" - # param in __init__. Use "self" - # if possible. - '__dataclass_self__' if 'self' in fields - else 'self', - globals, - slots, - )) + _init_fn(all_init_fields, + std_init_fields, + kw_only_init_fields, + frozen, + has_post_init, + # The name to use for the "self" + # param in __init__. Use "self" + # if possible. + '__dataclass_self__' if 'self' in fields + else 'self', + func_builder, + slots, + ) + _set_new_attribute(cls, '__replace__', _replace) # Get the fields as a list, and include only real fields. This is @@ -1067,7 +1098,13 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, if repr: flds = [f for f in field_list if f.repr] - _set_new_attribute(cls, '__repr__', _repr_fn(flds, globals)) + func_builder.add_fn('__repr__', + ('self',), + [' return f"{self.__class__.__qualname__}(' + + ', '.join([f"{f.name}={{self.{f.name}!r}}" + for f in flds]) + ')"'], + locals={'__dataclasses_recursive_repr': recursive_repr}, + decorator="@__dataclasses_recursive_repr()") if eq: # Create __eq__ method. There's no need for a __ne__ method, @@ -1075,16 +1112,13 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, cmp_fields = (field for field in field_list if field.compare) terms = [f'self.{field.name}==other.{field.name}' for field in cmp_fields] field_comparisons = ' and '.join(terms) or 'True' - body = [f'if self is other:', - f' return True', - f'if other.__class__ is self.__class__:', - f' return {field_comparisons}', - f'return NotImplemented'] - func = _create_fn('__eq__', - ('self', 'other'), - body, - globals=globals) - _set_new_attribute(cls, '__eq__', func) + func_builder.add_fn('__eq__', + ('self', 'other'), + [ ' if self is other:', + ' return True', + ' if other.__class__ is self.__class__:', + f' return {field_comparisons}', + ' return NotImplemented']) if order: # Create and set the ordering methods. @@ -1096,18 +1130,19 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, ('__gt__', '>'), ('__ge__', '>='), ]: - if _set_new_attribute(cls, name, - _cmp_fn(name, op, self_tuple, other_tuple, - globals=globals)): - raise TypeError(f'Cannot overwrite attribute {name} ' - f'in class {cls.__name__}. Consider using ' - 'functools.total_ordering') + # Create a comparison function. If the fields in the object are + # named 'x' and 'y', then self_tuple is the string + # '(self.x,self.y)' and other_tuple is the string + # '(other.x,other.y)'. + func_builder.add_fn(name, + ('self', 'other'), + [ ' if other.__class__ is self.__class__:', + f' return {self_tuple}{op}{other_tuple}', + ' return NotImplemented'], + overwrite_error='Consider using functools.total_ordering') if frozen: - for fn in _frozen_get_del_attr(cls, field_list, globals): - if _set_new_attribute(cls, fn.__name__, fn): - raise TypeError(f'Cannot overwrite attribute {fn.__name__} ' - f'in class {cls.__name__}') + _frozen_get_del_attr(cls, field_list, func_builder) # Decide if/how we're going to create a hash function. hash_action = _hash_action[bool(unsafe_hash), @@ -1115,9 +1150,12 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, bool(frozen), has_explicit_hash] if hash_action: - # No need to call _set_new_attribute here, since by the time - # we're here the overwriting is unconditional. - cls.__hash__ = hash_action(cls, field_list, globals) + cls.__hash__ = hash_action(cls, field_list, func_builder) + + # Generate the methods and add them to the class. This needs to be done + # before the __doc__ logic below, since inspect will look at the __init__ + # signature. + func_builder.add_fns_to_class(cls) if not getattr(cls, '__doc__'): # Create a class doc-string. @@ -1130,7 +1168,7 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, cls.__doc__ = (cls.__name__ + text_sig) if match_args: - # I could probably compute this once + # I could probably compute this once. _set_new_attribute(cls, '__match_args__', tuple(f.name for f in std_init_fields)) diff --git a/Misc/NEWS.d/next/Core and Builtins/2023-10-14-00-05-17.gh-issue-109870.oKpJ3P.rst b/Misc/NEWS.d/next/Core and Builtins/2023-10-14-00-05-17.gh-issue-109870.oKpJ3P.rst new file mode 100644 index 0000000..390bb12 --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2023-10-14-00-05-17.gh-issue-109870.oKpJ3P.rst @@ -0,0 +1,3 @@ +Dataclasses now calls :func:`exec` once per dataclass, instead of once +per method being added. This can speed up dataclass creation by up to +20%. |