################################################################
# basic build/use logs
################################################################


[mark@toy ~/PP2ndEd/dev/examples/Part3/Extend]$ make -f makefile.hello
gcc hello.c -g -I/home/mark/python1.5.2-ddjcd/Python-1.5.2/Include -I/home/mark/python1.5.2-ddjcd/Python-1.5.2 -fpic -shared -o hello.so


[mark@toy ~/PP2ndEd/dev/examples/Part3/Extend]$ python
Python 1.5.2 (#14, Sep 12 1999, 00:55:49)  [GCC egcs-2.91.66 19990314/Linux (egcs- on linux2
Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam
>>> import hello
>>> hello.message('world')
'Hello, world'
>>> hello.message('extending')
'Hello, extending'
>>>
>>> dir(hello)
['__doc__', '__file__', '__name__', 'message']
>>>
>>> hello.__name__, hello.__file__
('hello', './hello.so')
>>>                                                

>>> import hello
>>> hello.nonesuch()
Traceback (innermost last):
  File "<stdin>", line 1, in ?
AttributeError: nonesuch
>>>
>>> hello.message('a', 'b')
Traceback (innermost last):
  File "<stdin>", line 1, in ?
TypeError: 1-sequence, 2-sequence
>>>
>>> hello.message(42)
Traceback (innermost last):
  File "<stdin>", line 1, in ?
TypeError: argument 1: expected string, int found
>>> hello.message('C')
'Hello, C'
>>>                                                



################################################################
# run a program which uses the extension 
################################################################


[mark@toy ~/PP2ndEd/dev/examples/Part3/Extend]$ python hellouse.py
Hello, C
Hello, module ./hello.so
Hello, 0
Hello, 1
Hello, 2                          



###############################################################
# reload() doesn't crash on dynamically-loaded C extension 
# modules, but resets the module's attributes to their 
# original values (at the first import); internally, Python
# saves the modules attribute dictionary after the module 
# is first imported and initialized, and runs a dict.update()
# call on the current dictionary with the one saved; note 
# that Python does not actually reload the module's .so file
# if it has changed, so reload() is more like a rollback/reset
# for C extension modules, rather than an actual reload/rerun
# as it is for Python modules.
###############################################################

[mark@toy ~/PP2ndEd/dev/examples/Part3/Extend]$ python -v
...

>>> import hello
import hello # dynamically loaded from ./hello.so
>>> hello.message('xxx')
'Hello, xxx'
>>> hello.message
<built-in function message>
>>> hello
<module 'hello' from './hello.so'> 
>>>
>>>
>>> hello.message = 999
>>> hello.message
999
>>> hello.message('xxx')
Traceback (innermost last):
  File "<stdin>", line 1, in ?
TypeError: call of non-function (type int)
>>>
>>>
>>> reload(hello)
import hello # previously loaded (./hello.so)
<module 'hello' from './hello.so'>
>>>
>>> hello.message
<built-in function message>
>>> hello.message('xxx')
'Hello, xxx'
>>>


#
# try changing and reloading a C extension module
#


[mark@toy ~/test/Hello]$ python
>>>
>>> import hello
>>> hello.message('xxx')
'Hello, xxx'

... change hello.c and recompile the hello.so file in another window ...

>>> reload(hello)                             # just resets attr dict
<module 'hello' from './hello.so'>            # does not reload .so
>>> hello.message('xxx')                      # .so changes not seen
'Hello, xxx'
>>>

[mark@toy ~/test/Hello]$ python
>>> import hello
>>> hello.message('xxx')            # restarting picks up new .so contents
'BYE, xxx'
>>>                                 # reload only reloads python modules;
                                    # must restart to reload C extension mods