Python 3.10 match如何比较1和True？
How does Python 3.10 match compares 1 and True?
PEP 622, Literal Patterns 表示如下：
Note that because equality (__eq__) is used, and the equivalency between Booleans and the integers 0 and 1, there is no practical difference between the following two:
case True:
...
case 1:
...
and True.__eq__(1) and (1).__eq__(True) both returns True, but when I 运行 these two code snippets with CPython, it seems like case True and case 1不一样。
$ python3.10
>>> match 1:
... case True:
... print('a') # not executed
...
>>> match True:
... case 1:
... print('a') # executed
...
a
1 和 True 实际比较如何？
查看模式匹配规范，这属于 "literal pattern":
A literal pattern succeeds if the subject value compares equal to the
value expressed by the literal, using the following comparisons rules:
- Numbers and strings are compared using the == operator.
- The singleton literals None, True and False are compared using the is
operator.
所以当模式是：
case True:
使用is，1 is True为false。另一方面，
case 1:
使用 ==，1 == True 为真。
PEP 622, Literal Patterns 表示如下：
Note that because equality (__eq__) is used, and the equivalency between Booleans and the integers 0 and 1, there is no practical difference between the following two:
case True: ... case 1: ...
and True.__eq__(1) and (1).__eq__(True) both returns True, but when I 运行 these two code snippets with CPython, it seems like case True and case 1不一样。
$ python3.10
>>> match 1:
... case True:
... print('a') # not executed
...
>>> match True:
... case 1:
... print('a') # executed
...
a
1 和 True 实际比较如何？
查看模式匹配规范，这属于 "literal pattern":
A literal pattern succeeds if the subject value compares equal to the value expressed by the literal, using the following comparisons rules:
- Numbers and strings are compared using the == operator.
- The singleton literals None, True and False are compared using the is operator.
所以当模式是：
case True:
使用is，1 is True为false。另一方面，
case 1:
使用 ==，1 == True 为真。