[Python编程(第4版)].(Programming.Python.4th.Edition).Mark.Lutz.文字版

standard module and filename attributes, though the filename doesn’t end in a .py
or .pyc this time around—the only obvious way you can tell it’s a C library:

>>> dir(hello) # C module attributes

['__doc__', '__file__', '__name__', '__package__', 'message']

>>> hello.__name__, hello.__file__

('hello', 'hello.dll')

>>> hello.message # a C function object

<built-in function message>

>>> hello # a C module object

<module 'hello' from 'hello.dll'>

>>> hello.__doc__ # docstrings in C code

'mod doc'

>>> hello.message.__doc__

'func doc'

>>> hello.message() # errors work too

TypeError: argument must be sequence of length 1, not 0

Like any module in Python, you can also access the C extension from a script file. The
Python file in Example 20-3, for instance, imports and uses the C extension module in
Example 20-1.

Example 20-3. PP4E\Integrate\Extend\Hello\hellouse.py

"import and use a C extension library module"

import hello
print(hello.message('C'))
print(hello.message('module ' + hello.file))

for i in range(3):
reply = hello.message(str(i))
print(reply)

Run this script as any other—when the script first imports the module hello, Python
automatically finds the C module’s .dll object file in a directory on the module search
path and links it into the process dynamically. All of this script’s output represents
strings returned from the C function in the file hello.c:

.../PP4E/Integrate/Extend/Hello$ python hellouse.py

Hello, C

Hello, module /cygdrive/c/.../PP4E/Integrate/Extend/Hello/hello.dll

Hello, 0

Hello, 1

Hello, 2

See Python’s manuals for more details on the code in our C module, as well as tips for
compilation and linkage. Of note, as an alternative to makefiles, also see the
disthello.py and disthello-alt.py files in the examples package. Here’s a quick peek at
the source code of the first of these:

1490 | Chapter 20: Python/C Integration