Python重载__init__

我如何__init__()在Python中重载？我已经习惯了C/C++,其中编译器可以看到数据类型的差异,但由于Python中没有数据类型,当我将字符串作为参数时,如何确保调用第三个方法而不是第二个方法而不是一个int？

class Handle:
    def __init__(self):
        self.pid = -1

    def __init__(self, pid):
        self.pid = pid

    def __init__(self, procname):
        print(procname)
        self.pid = -1 # find pid by name

Andrea Corbe.. 6

在C++中,您可以定义具有相同名称和不同签名的多个函数/方法.在Python中,每次定义一个与之前定义的函数同名的新函数时,都要替换它.

要实现您想要的,您必须使用可选参数和/或显式检查.

以下是一些可能的解决方案:

class Handle:
    def __init__(self, pid=-1):
        if isinstance(pid, str):
            self.procname = pid
            self.pid = -1
        else:
            self.procname = None
            self.pid = pid

class Handle:
    # Both pid and procname may be specified at the same time.
    def __init__(self, pid=-1, procname=None):
        self.procname = procname
        self.pid = pid

class Handle:
    # Either pid or procname, not both, may be specified.
    def __init__(self, pid=-1, procname=None):
        if pid >= 0 and procname is not None:
            raise ValueError('you can specify either pid or procname, not both')
        self.procname = procname
        self.pid = pid

class Handle:
    def __init__(self, pid=-1):
        self.pid = pid

    # A separate constructor, with a different name,
    # because "explicit is better than implicit" and
    # "sparse is better than dense" (cit. The Zen of
    # Python).
    # In my opinion, this is the most Pythonic solution.
    @classmethod
    def from_process_name(cls, procname):
        pid = get_pid(procname)
        return cls(pid)

顺便说一句,我不建议使用-1"未指定".我宁愿用None.

在C++中,您可以定义具有相同名称和不同签名的多个函数/方法.在Python中,每次定义一个与之前定义的函数同名的新函数时,都要替换它.

要实现您想要的,您必须使用可选参数和/或显式检查.

以下是一些可能的解决方案:

class Handle:
    def __init__(self, pid=-1):
        if isinstance(pid, str):
            self.procname = pid
            self.pid = -1
        else:
            self.procname = None
            self.pid = pid

class Handle:
    # Both pid and procname may be specified at the same time.
    def __init__(self, pid=-1, procname=None):
        self.procname = procname
        self.pid = pid

class Handle:
    # Either pid or procname, not both, may be specified.
    def __init__(self, pid=-1, procname=None):
        if pid >= 0 and procname is not None:
            raise ValueError('you can specify either pid or procname, not both')
        self.procname = procname
        self.pid = pid

class Handle:
    def __init__(self, pid=-1):
        self.pid = pid

    # A separate constructor, with a different name,
    # because "explicit is better than implicit" and
    # "sparse is better than dense" (cit. The Zen of
    # Python).
    # In my opinion, this is the most Pythonic solution.
    @classmethod
    def from_process_name(cls, procname):
        pid = get_pid(procname)
        return cls(pid)

顺便说一句,我不建议使用-1"未指定".我宁愿用None.