[Python-Dev] Changing select.select to accept iterables

[Brett C.]

Guido van Rossum wrote:

>>>[Brett, about <http://www.python.org/sf/798046>]
> 
> Since Tim thinks it's okay to change (and since I now know what the OP
> wanted) you have my blessing to give this a try.
> 

OK, done.  I tore out the PyList_Check in select_select() and just put 
the PySequence_Fast() call in list2set(), which I renamed seq2set(), so 
as to centralize the code and make managing refcounts simpler.  I pasted 
in an interpreter session at the end of this email showing some checking 
I did to make sure I didn't botch anything.  If someone could 
double-check them and see if they can think of something I may have 
missed I would appreciate it.

I made the docstring (as seen below) say that the arguments must be 
sequences since that is what PySequence_Fast says it takes in, although 
it obviously works with containers.  Any objections?

Assuming no one can think of anything that I missed I will then commit 
(with appropriate Misc/NEWS and doc changes), change the bug report to 
an feature request since that is what it really is, and close it.

-Brett



[passes test_select...]
 >>> import test.test_select
timeout = 0
'testing...\n'
timeout = 1
'testing...\n'
timeout = 2
'testing...\n'
timeout = 4
'testing...\n'
timeout = 8
'testing...\n'
timeout = 16
'testing...\n'
timeout = None
'testing...\n'
timeout = None
'testing...\n'
timeout = None
'testing...\n'
timeout = None
'testing...\n'
timeout = None
''
EOF
[24363 refs]

[works with sets as requested...]
 >>> from sets import Set
[26557 refs]
 >>> from select import select
[26559 refs]
 >>> read_FILE = file("README", 'r')
[26567 refs]
 >>> write_FILE = file("@test", 'w')
[26574 refs]
 >>> print select(Set([write_FILE]), Set([read_FILE]), [], 0)
([<open file '@test', mode 'w' at 0x5051e0>], [<open file 'README', mode 
'r' at 0x486550>], [])
[26607 refs]


[modified docstring to say it works with sequences...]
 >>> help(select)
Help on built-in function select:

select(...)
     select(rlist, wlist, xlist[, timeout]) -> (rlist, wlist, xlist)

     Wait until one or more file descriptors are ready for some kind of I/O.
     The first three arguments are sequences of file descriptors to be 
waited for:
...


[new error message on improper arguments...]
 >>> print select(1, 2, 3, 0)
Traceback (most recent call last):
   File "<stdin>", line 1, in ?
TypeError: arguments 1-3 must be sequences
[39435 refs]

[managed to not screw up refcounts =) ...]
 >>> print select(Set([write_FILE]), Set([read_FILE]), [], 0)
([<open file '@test', mode 'w' at 0x5051e0>], [<open file 'README', mode 
'r' at 0x486550>], [])
[39435 refs]
 >>> print select(Set([write_FILE]), Set([read_FILE]), [], 0)
([<open file '@test', mode 'w' at 0x5051e0>], [<open file 'README', mode 
'r' at 0x486550>], [])
[39435 refs]


[... and of course still works the way it originally did.]
 >>> print select([write_FILE], [read_FILE], [], 0)
([<open file '@test', mode 'w' at 0x5051e0>], [<open file 'README', mode 
'r' at 0x486550>], [])
[39435 refs]