convert ftp.retrbinary to file object? - Python language lacks expression?

[Robert]

That turns into periodic new RETR commands with offset. Think its more 
an "odd" trick. I'd even prefer a threaded approach (thread puts the 
blocks into a stack; a while ... yield generator loop in the main thread 
serves the .read() function of the pseudo file object, which is my 
wish). Yet such tricks are all kind of OS-level tricks with a lot of 
overhead.

I wonder really, if the Python language itself can express an elegant 
flat solution to turn the block delivering callback function into a 
generator/.read(bytes) solution? I found no way.

(Looking over some Ruby stuff, Ruby seems to be able to do so from the 
language. I am not really familiar to Ruby. I always felt Python to be 
as complete - but much more clean. I became somewhat jealous ... :-) )

As the solution in my case has to stand many different file systems 
compatibly ( file.read(bytes) function !) and also other FTPS & SFTP 
classes with different retrbinary functions have to be compatible, I 
cannot even make a simple FTP subclassed retrbinary without getting 
really weired. Thus the existing .retrbinary with callback is the 
"official interface in this game".



 > >>     def callback(self, data):
 > >>         self.offset = self.offset + len(data)
 > >>         self.data = data
 > >>         ## now quit the RETR command?
 > >>         raise TransferAbort("stop right now")