* Enum: streamline repr() and str(); improve docs
- repr() is now ``enum_class.member_name``
- stdlib global enums are ``module_name.member_name``
- str() is now ``member_name``
- add HOW-TO section for ``Enum``
- change main documentation to be an API reference
In 3.5 (?) a speed optimization made it possible to access members as
attributes of other members, i.e. ``Color.RED.BLUE``. This was always
discouraged in the docs, and other recent optimizations has made that
one no longer necessary. Because some may be relying on it anyway, it
is being deprecated in 3.10, and will be removed in 3.11.
Flag members are now divided by one-bit verses multi-bit, with multi-bit being treated as aliases. Iterating over a flag only returns the contained single-bit flags.
Iterating, repr(), and str() show members in definition order.
When constructing combined-member flags, any extra integer values are either discarded (CONFORM), turned into ints (EJECT) or treated as errors (STRICT). Flag classes can specify which of those three behaviors is desired:
>>> class Test(Flag, boundary=CONFORM):
... ONE = 1
... TWO = 2
...
>>> Test(5)
<Test.ONE: 1>
Besides the three above behaviors, there is also KEEP, which should not be used unless necessary -- for example, _convert_ specifies KEEP as there are flag sets in the stdlib that are incomplete and/or inconsistent (e.g. ssl.Options). KEEP will, as the name suggests, keep all bits; however, iterating over a flag with extra bits will only return the canonical flags contained, not the extra bits.
Iteration is now in member definition order. If member definition order
matches increasing value order, then a more efficient method of flag
decomposition is used; otherwise, sort() is called on the results of
that method to get definition order.
``re`` module:
repr() has been modified to support as closely as possible its previous
output; the big difference is that inverted flags cannot be output as
before because the inversion operation now always returns the comparable
positive result; i.e.
re.A|re.I|re.M|re.S is ~(re.L|re.U|re.S|re.T|re.DEBUG)
in both of the above terms, the ``value`` is 282.
re's tests have been updated to reflect the modifications to repr().
`type.__new__` calls `__set_name__` and `__init_subclass__`, which means
that any work metaclasses do after calling `super().__new__()` will not
be available to those two methods. In particular, `Enum` classes that
want to make use of `__init_subclass__` will not see any members.
Almost all customization is therefore moved to before the
`type.__new__()` call, including changing all members to a proto member
descriptor with a `__set_name__` that will do the final conversion of a
member to be an instance of the `Enum` class.
This allows easier Enum construction in unusual cases, such as including dynamic member definitions into a class definition:
# created dynamically
foo_defines = {'FOO_CAT': 'aloof', 'BAR_DOG': 'friendly', 'FOO_HORSE': 'big'}
class Foo(Enum):
vars().update({
k: v
for k, v in foo_defines.items()
if k.startswith('FOO_')
})
def upper(self):
# example method
return self.value.upper()
The default for auto() is to return an integer, which doesn't work for `StrEnum`. The new `_generate_next_value_` for `StrEnum` returns the member name, lower cased.
When creating an Enum, type.__new__ calls __init_subclass__, but at that point the members have not been added.
This patch suppresses the initial call, then manually calls the ancestor __init_subclass__ before returning the new Enum class.
EnumMeta double-checks that `__repr__`, `__str__`, `__format__`, and `__reduce_ex__` are not the same as `object`'s, and replaces them if they are -- even if that replacement was intentionally done in the Enum being constructed. This patch fixes that.
Automerge-Triggered-By: @ethanfurman
Capturing exceptions into names can lead to reference cycles though the __traceback__ attribute of the exceptions in some obscure cases that have been reported previously and fixed individually. As these variables are not used anyway, we can remove the binding to reduce the chances of creating reference cycles.
See for example GH-13135
* bpo-31801: Enum: add _ignore_ as class option
_ignore_ is a list, or white-space seperated str, of names that will not
be candidates for members; these names, and _ignore_ itself, are removed
from the final class.
* bpo-31801: Enum: add documentation for _ignore_
* bpo-31801: Enum: remove trailing whitespace
* bpo-31801: Enum: fix bulleted list format
* bpo-31801: add version added for _ignore_
Ethan Furman
Angelin BOOZ
Zackery Spytz
Ethan Onstott
HongWeipeng
Pablo Galindo
HongWeipeng
Walter Dörwald
thatneat
Zachary Ware
Brennan D Baraban
Rémi Lapeyre
Andrew Svetlov
orlnub123
Rahul Jha
INADA Naoki
anentropic
Serhiy Storchaka
Ville Skyttä
Dong-hee Na
Raymond Hettinger