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February 1, 2018 08:38
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生成器
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class FileWrapper(object): | |
def __init__(self, file, buf_size=8192): | |
self.file = file | |
self.buf_size = buf_size | |
def close(self): | |
if hasattr(self.file, 'close'): | |
self.file.close() | |
def __iter__(self): | |
return self | |
def __next__(self): | |
data = self.file.read(self.buf_size) | |
if data: | |
return data | |
raise StopIteration() |
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def call(f): | |
return f() | |
@list | |
@call | |
def fib(): | |
a, b = 0, 1 | |
for _ in range(10): | |
yield a | |
a, b = b, a + b | |
print fib() |
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def gen(): | |
a = yield 1 | |
yield a | |
f = gen() | |
f.send(None) # 1 | |
f.send(2) # 2 |
生成器生成顺序
- 以发送 None 信号开始
- 先返回值,挂起, 等待信号
- 发送信号,执行到下一个yield并返回值
- 最后 抛出
StopIteration
异常
file_iterator.py
next 的用法, 只生成当前值因为会多次调用 避免了写循环
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list 的用法
list()
生成空列表list(iterable)
生成新列表, 包含以前的元素