68 lines
1.7 KiB
Python
68 lines
1.7 KiB
Python
#!/usr/bin/env python
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# -*- encoding: utf-8 -*-
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"""
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Topic: 让对象支持上下文管理器
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Desc :
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"""
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from socket import socket, AF_INET, SOCK_STREAM
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class LazyConnection:
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def __init__(self, address, family=AF_INET, type=SOCK_STREAM):
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self.address = address
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self.family = family
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self.type = type
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self.sock = None
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def __enter__(self):
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if self.sock is not None:
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raise RuntimeError('Already connected')
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self.sock = socket(self.family, self.type)
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self.sock.connect(self.address)
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return self.sock
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def __exit__(self, exc_ty, exc_val, tb):
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self.sock.close()
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self.sock = None
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from functools import partial
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conn = LazyConnection(('www.python.org', 80))
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# Connection closed
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with conn as s:
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# conn.__enter__() executes: connection open
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s.send(b'GET /index.html HTTP/1.0\r\n')
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s.send(b'Host: www.python.org\r\n')
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s.send(b'\r\n')
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resp = b''.join(iter(partial(s.recv, 8192), b''))
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print(resp)
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# conn.__exit__() executes: connection closed
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class LazyConnection2:
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def __init__(self, address, family=AF_INET, type=SOCK_STREAM):
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self.address = address
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self.family = family
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self.type = type
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self.connections = []
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def __enter__(self):
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sock = socket(self.family, self.type)
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sock.connect(self.address)
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self.connections.append(sock)
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return sock
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def __exit__(self, exc_ty, exc_val, tb):
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self.connections.pop().close()
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# Example use
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from functools import partial
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conn = LazyConnection2(('www.python.org', 80))
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with conn as s1:
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pass
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with conn as s2:
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pass
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# s1 and s2 are independent sockets |