为什么在 `float.is_integer` 中有下划线，而在 `str.isnumeric` 中没有？
Why an underscore in `float.is_integer`, but not in `str.isnumeric`?
float.is_integer is the only "is" method with an underscore in its name among built-in types in Python. Examples that don't 似乎包含下划线：str.isalnum、str.isalpha、str.isdecimal、str.isdigit、str.isidentifier、str.islower, str.isnumeric, str.isprintable, str.isspace, str.istitle, str.isupper.
关于原因的任何线索？
By PEP 8, I would expect all these names to include an underscore. But practicality beats purity (PEP 20)，因此省略常用名称和短名称中的下划线是有意义的。然而，这两种命名约定似乎都是向后兼容的结果（以 logging 模块作为典型示例）。
similar question 已在 Python 错误跟踪器上被问到：
Compare isinstance, issubclass, and islower to is_integer, is_fifo, and is_enabled. In Python 3.6, of all the names in the standard library starting with is, I count 69 names with the underscore and 91 without. It seems better to pick one way or the other and stick with it. I would recommend using the underscore, for legibility.
答案（来自 Python 核心开发人员 R. David Murray）是：
Yep, that would be nice. But Python has evolved over time, and we must maintain backward compatibility. The names are what they are.
鉴于问题中的数字，似乎 is_integer 不是唯一带有下划线的方法。
float.is_integer is the only "is" method with an underscore in its name among built-in types in Python. Examples that don't 似乎包含下划线：str.isalnum、str.isalpha、str.isdecimal、str.isdigit、str.isidentifier、str.islower, str.isnumeric, str.isprintable, str.isspace, str.istitle, str.isupper.
关于原因的任何线索？
By PEP 8, I would expect all these names to include an underscore. But practicality beats purity (PEP 20)，因此省略常用名称和短名称中的下划线是有意义的。然而，这两种命名约定似乎都是向后兼容的结果（以 logging 模块作为典型示例）。
similar question 已在 Python 错误跟踪器上被问到：
Compare
isinstance,issubclass, andislowertois_integer,is_fifo, andis_enabled. In Python 3.6, of all the names in the standard library starting withis, I count 69 names with the underscore and 91 without. It seems better to pick one way or the other and stick with it. I would recommend using the underscore, for legibility.
答案（来自 Python 核心开发人员 R. David Murray）是：
Yep, that would be nice. But Python has evolved over time, and we must maintain backward compatibility. The names are what they are.
鉴于问题中的数字，似乎 is_integer 不是唯一带有下划线的方法。