我只是好奇内置函数'print'在Python3的幕后如何工作。因此,以下代码段是我尝试编写自己的打印功能的尝试,但是我不确定它是否准确表示实际“打印”的工作方式:
import os
import sys
def my_print(*args, **kwargs):
sep = kwargs.get('sep', ' ')
end = kwargs.get('end', os.linesep)
if end is None:
end = os.linesep
file = kwargs.get('file', sys.stdout)
flush = kwargs.get('flush', False)
file.write('%s%s' % (sep.join(str(arg) for arg in args), end))
if flush:
file.flush()
如果有人知道内置“打印”的工作原理,评估我的版本的准确性并指出任何不足之处,我将不胜感激。
print
是Python 3中的内置函数。大多数内置函数都是用C实现的(无论如何,在默认的CPython解释器中),print
也不例外。实现是builtin_print
中的Python/bltinmodule.c
,可以在此处看到:https://github.com/python/cpython/blob/v3.8.0/Python/bltinmodule.c#L1821
另一方面,PyPy解释器是在Python的子集中实现的,因此它具有在print
中用Python编写的pypy/module/__builtin__/app_io.py
函数,可以在此处看到:https://bitbucket.org/pypy/pypy/src/5da45ced70e515f94686be0df47c59abd1348ebc/pypy/module/builtin/app_io.py#lines-59
这里是相关代码;相当短:
def print_(*args, **kwargs):
r"""print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
Prints the values to a stream, or to sys.stdout by default.
Optional keyword arguments:
file: a file-like object (stream); defaults to the current sys.stdout.
sep: string inserted between values, default a space.
end: string appended after the last value, default a newline.
flush: whether to forcibly flush the stream.
"""
fp = kwargs.pop("file", None)
if fp is None:
fp = sys.stdout
if fp is None:
return
def write(data):
fp.write(str(data))
sep = kwargs.pop("sep", None)
if sep is not None:
if not isinstance(sep, str):
raise TypeError("sep must be None or a string")
end = kwargs.pop("end", None)
if end is not None:
if not isinstance(end, str):
raise TypeError("end must be None or a string")
flush = kwargs.pop('flush', None)
if kwargs:
raise TypeError("invalid keyword arguments to print()")
if sep is None:
sep = " "
if end is None:
end = "\n"
for i, arg in enumerate(args):
if i:
write(sep)
write(arg)
write(end)
if flush:
fp.flush()