On 01/14/2011 12:51 PM, Chris Rebert wrote:
On Fri, Jan 14, 2011 at 7:52 AM, Cun Zhang<apzc2...@gmail.com> wrote:
Hi,all
I hope use cStringIO to create virtual file, but my customed function which
is from a shared library imported by ctypes
just accepts a filename(string type) as parameter.
So I'm wondering whether there is any method that make the virtual file
created by cStringIO like a normal file which have
a filename, so it can be called by my functions.
That's not possible. (c)StringIO presents a file-like interface at the
Python level, but under the covers, it's not implemented using
anything like a normal file; thus, it doesn't have a presence on any
filesystem. I would suggest using a temporary file
(http://docs.python.org/library/tempfile.html ) for communicating with
the C module, writing the contents of the StringIO object to the
temporary file if necessary.
(It's probably also possible to hack something together with FUSE, but
it'd be a slow, platform-specific kludge.)
Cheers,
Chris
--
http://blog.rebertia.com
However, as the only reason to have the cstringIO object have a name is
for you to open or close it. The rest of the functionality is the same,
reading and writing too.
------------------
in a terminal ...
import cStringIO
ab = cStringIO.StringIO() # an output type, as it was call with nothing.
cd = cStringIO.StringIO( 'a filled buffer') # an input type.
type( ab ) == cStringIO.OutputType
True
type( cd ) == cStringIO.InputType
True
Working with these properties .... we get
Let's assume you have class with read and write ability,
which assumes opening a file or cStringIO object (could
extend to StringIO object with out much changing ).
class foo:
def __init__( self ):
""" Define some variables. House keeping. """
self.readState = False
self.writeState = False
self.readObj = None
self.writeObj = None
def fooOpenWrite( self, fileobj ):
if type( fileobj ) === StringType:
self.writeObj = open( fileobj, 'wb' )
elif type( fileobj ) == cStringIO.OutputType:
self.writeObj = fileobj
else:
self.writeState = False
return
self.readState = True
return True
def fooOpenRead( self, fileobj ):
if type( fileobj ) === StringType:
self.readObj = open( fileobj, 'wb' )
elif type( fileobj ) == cStringIO.OutputType:
self.readObj = fileobj
else:
self.readState = False
return
self.readState = True
return
def fooRead( self ):
for x in self.readObj:
print x
def fooWrite( self, str ):
self.readObj.write( str )
Steven
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