fileinput
— 遍历来自多个输入流的行
¶
源代码： Lib/fileinput.py
此模块实现的帮手类和函数，能快速编写基于标准输入 (或文件列表) 的循环。若仅仅想要读写一个文件，见
open()
.
典型用法：
import fileinput for line in fileinput.input(): process(line)
这遍历所有文件的行，文件列出于
sys.argv[1:]
，默认为
sys.stdin
若列表为空。若文件名为
'-'
，它也被替换为
sys.stdin
和可选自变量
mode
and
openhook
被忽略。要指定文件名的替代列表，将它作为第一自变量传递给
input()
。单文件名也是允许的。
默认情况下，所有文件按文本模式打开，但可以覆盖这通过指定
mode
参数在调用
input()
or
FileInput
。若在打开 (或读取) 文件期间出现 I/O 错误，
OSError
被引发。
3.3 版改变：
IOError
曾被引发；它现在是别名化的
OSError
.
若
sys.stdin
被多次使用，第二次和进一步使用将不返回行 (除或许为交互使用外)，或者若它被明确重置 (如使用
sys.stdin.seek(0)
).
打开空文件会立即关闭；它们出现在文件名列表中的唯一一次，是在最后打开的文件为空时。
行与任何完整换行符一起返回，意味着文件中的最后行可能没有换行符。
可以控制如何打开文件通过提供打开挂钩凭借
openhook
参数用于
fileinput.input()
or
FileInput()
。挂钩必须是接受 2 自变量的函数，
filename
and
mode
，并返回故此打开的像文件对象。此模块已提供 2 个有用挂钩。
以下函数是此模块的首要接口：
fileinput.
input
(
files=None
,
inplace=False
,
backup=''
,
*
,
mode='r'
,
openhook=None
)
¶
创建实例化的
FileInput
类。实例将用作此模块函数的全局状态，且还返回以用于迭代期间。将传递此函数的参数沿构造函数对于
FileInput
类。
The
FileInput
实例可以用作上下文管理器在
with
语句。在此范例中，
input
被关闭后于
with
语句的退出，即使发生异常：
with fileinput.input(files=('spam.txt', 'eggs.txt')) as f: for line in f: process(line)
3.2 版改变： 可以用作上下文管理器。
3.8 版改变： 关键词参数 mode and openhook 现在是仅关键词。
以下函数使用的全局状态创建通过
fileinput.input()
；若没有活动状态，
RuntimeError
被引发。
fileinput.
filename
(
)
¶
Return the name of the file currently being read. Before the first line has been read, returns
None
.
fileinput.
fileno
(
)
¶
Return the integer “file descriptor” for the current file. When no file is opened (before the first line and between files), returns
-1
.
fileinput.
lineno
(
)
¶
Return the cumulative line number of the line that has just been read. Before the first line has been read, returns
0
. After the last line of the last file has been read, returns the line number of that line.
fileinput.
filelineno
(
)
¶
Return the line number in the current file. Before the first line has been read, returns
0
. After the last line of the last file has been read, returns the line number of that line within the file.
fileinput.
isfirstline
(
)
¶
返回
True
if the line just read is the first line of its file, otherwise return
False
.
fileinput.
isstdin
(
)
¶
返回
True
若最后行读取自
sys.stdin
，否则返回
False
.
fileinput.
nextfile
(
)
¶
Close the current file so that the next iteration will read the first line from the next file (if any); lines not read from the file will not count towards the cumulative line count. The filename is not changed until after the first line of the next file has been read. Before the first line has been read, this function has no effect; it cannot be used to skip the first file. After the last line of the last file has been read, this function has no effect.
fileinput.
close
(
)
¶
关闭序列。
The class which implements the sequence behavior provided by the module is available for subclassing as well:
fileinput.
FileInput
(
files=None
,
inplace=False
,
backup=''
,
*
,
mode='r'
,
openhook=None
)
¶
类
FileInput
是实现；其方法
filename()
,
fileno()
,
lineno()
,
filelineno()
,
isfirstline()
,
isstdin()
,
nextfile()
and
close()
correspond to the functions of the same name in the module. In addition it has a
readline()
method which returns the next input line, and a
__getitem__()
method which implements the sequence behavior. The sequence must be accessed in strictly sequential order; random access and
readline()
cannot be mixed.
采用
mode
you can specify which file mode will be passed to
open()
。它必须是某一
'r'
,
'rU'
,
'U'
and
'rb'
.
The openhook , when given, must be a function that takes two arguments, filename and mode , and returns an accordingly opened file-like object. You cannot use inplace and openhook 在一起。
A
FileInput
实例可以用作上下文管理器在
with
语句。在此范例中，
input
被关闭后于
with
语句的退出，即使发生异常：
with FileInput(files=('spam.txt', 'eggs.txt')) as input: process(input)
3.2 版改变： 可以用作上下文管理器。
从 3.4 版起弃用：
The
'rU'
and
'U'
模式。
从 3.8 版起弃用：
支持
__getitem__()
方法被弃用。
3.8 版改变： 关键词参数 mode and openhook 现在是仅关键词。
可选原位过滤：
若关键词自变量
inplace=True
被传递给
fileinput.input()
or to the
FileInput
constructor, the file is moved to a backup file and standard output is directed to the input file (if a file of the same name as the backup file already exists, it will be replaced silently). This makes it possible to write a filter that rewrites its input file in place. If the
backup
parameter is given (typically as
backup='.<some extension>'
), it specifies the extension for the backup file, and the backup file remains around; by default, the extension is
'.bak'
and it is deleted when the output file is closed. In-place filtering is disabled when standard input is read.
此模块提供以下 2 打开挂钩：
fileinput.
hook_compressed
(
filename
,
mode
)
¶
Transparently opens files compressed with gzip and bzip2 (recognized by the extensions
'.gz'
and
'.bz2'
) 使用
gzip
and
bz2
modules. If the filename extension is not
'.gz'
or
'.bz2'
, the file is opened normally (ie, using
open()
without any decompression).
用法范例：
fi = fileinput.FileInput(openhook=fileinput.hook_compressed)