Jython的操作符重载
像 C++ 一样，但是与 Java 语言不同，Jython 允许类重载许多标准语言操作符。这意味着类可以为语言操作符定义特定的意义。 Jython 还允许类模仿内置类型，如数字、序列和映射。
在下面的例子中，我们将使用标准 Jython UserList 类定义展示实际的操作符重载的例子.UserList 是一个包装了一个列表的类，它的行为也像列表。它的大多数函数都 指派（传递）给其包含的列表，称为data。在一个更实际的Jython操作符重载的例子中，会实现这些重载的函数以访问其他一些存储，如磁盘文件或者数据库。
- class UserList:
- def __init__(self, initlist=None):
- self.data = []
- if initlist is not None:
- if type(initlist) == type(self.data):
- self.data[:] = initlist
- elif isinstance(initlist, UserList):
- self.data[:] = initlist.data[:]
- else:
- self.data = list(initlist)
- def __cast(self, other):
- if isinstance(other, UserList): return other.data
- else: return other
- # `self`, repr(self)
- def __repr__(self): return repr(self.data)
- # self < other
- def __lt__(self, other): return self.data < self.__cast(other)
- # self <= other
- def __le__(self, other): return self.data <= self.__cast(other)
- # self == other
- def __eq__(self, other): return self.data == self.__cast(other)
- # self != other, self <> other
- def __ne__(self, other): return self.data != self.__cast(other)
- # self > other
- def __gt__(self, other): return self.data > self.__cast(other)
- # self >= other
- def __ge__(self, other): return self.data >= self.__cast(other)
- # cmp(self, other)
- def __cmp__(self, other):
- raise RuntimeError, "UserList.__cmp__() is obsolete"
- # item in self
- def __contains__(self, item): return item in self.data
- # len(self)
- def __len__(self): return len(self.data)
- # self[i]
- def __getitem__(self, i): return self.data[i]
- # self[i] = item
- def __setitem__(self, i, item): self.data[i] = item
- # del self[i]
- def __delitem__(self, i): del self.data[i]
- # self[i:j]
- def __getslice__(self, i, j):
- i = max(i, 0); j = max(j, 0)
- return self.__class__(self.data[i:j])
- # self[i:j] = other
- def __setslice__(self, i, j, other):
- i = max(i, 0); j = max(j, 0)
- if isinstance(other, UserList):
- self.data[i:j] = other.data
- elif isinstance(other, type(self.data)):
- self.data[i:j] = other
- else:
- self.data[i:j] = list(other)
- # del self[i:j]
- def __delslice__(self, i, j):
- i = max(i, 0); j = max(j, 0)
- del self.data[i:j]
- # self + other (join)
- def __add__(self, other):
- if isinstance(other, UserList):
- return self.__class__(self.data + other.data)
- elif isinstance(other, type(self.data)):
- return self.__class__(self.data + other)
- else:
- return self.__class__(self.data + list(other))
- # other + self (join)
- def __radd__(self, other):
- if isinstance(other, UserList):
- return self.__class__(other.data + self.data)
- elif isinstance(other, type(self.data)):
- return self.__class__(other + self.data)
- else:
- return self.__class__(list(other) + self.data)
- # self += other (join)
- def __iadd__(self, other):
- if isinstance(other, UserList):
- self.data += other.data
- elif isinstance(other, type(self.data)):
- self.data += other
- else:
- self.data += list(other)
- return self
- # self * other (repeat)
- def __mul__(self, n):
- return self.__class__(self.data*n)
- __rmul__ = __mul__
- # self *= other (repeat)
- def __imul__(self, n):
- self.data *= n
- return self
- # implement "List" functions below:
- def append(self, item): self.data.append(item)
- def insert(self, i, item): self.data.insert(i, item)
- def pop(self, i=-1): return self.data.pop(i)
- def remove(self, item): self.data.remove(item)
- def count(self, item): return self.data.count(item)
- def index(self, item): return self.data.index(item)
- def reverse(self): self.data.reverse()
- def sort(self, *args): apply(self.data.sort, args)
- def extend(self, other):
- if isinstance(other, UserList):
- self.data.extend(other.data)
- else:
- self.data.extend(other)
以上就是Jython的操作符重载的一个实例。
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