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

[Martin Franklin]

Martin Franklin wrote:
> Martin Franklin wrote:
> 
>> Robert wrote:
>>
>>> I just tried to convert a (hugh size) ftp.retrbinary run into a
>>> pseudo-file object with .read(bytes) method in order to not consume
>>> 500MB on a copy operation.
> 
> 
> [snip]
> 
>>
>>
>> Hmmmm this is nearly there I think...:
> 
> 
> whoops... spoke too soon..


Trigger happy this morning...

> 
>>
>> import ftplib
>>
>> class TransferAbort(Exception): pass
>>
>> class FTPFile:
>>     def __init__(self, server, filename):
>>         self.server = server
>>         self.filename = filename
>>         self.offset = 0
>>
>>     def callback(self, data):
>>         self.offset = self.offset + len(data)
>>         self.data = data
>>         ## now quit the RETR command?
>>         raise TransferAbort("stop right now")
>>
>>     def read(self, amount):
>>         self.ftp = ftplib.FTP(self.server)
>>         self.ftp.login()
> 
> 
> 
> I needed to insert a time.sleep(0.1) here as the connections were
> falling over themselves - I guess testing with a blocksize of 24
> is a little silly.
> 
> 
>>         try:
>>             self.ftp.retrbinary("RETR %s" %self.filename, self.callback,
>>                 blocksize=amount,
>>                 rest=self.offset)
>>         except TransferAbort:

also need to close the ftp connection here!

                self.ftp.close()

>>             return self.data
>>
>>
>> f = FTPFile("HOSTNAME", "FILENAME")
>>
>> print f.read(24)
>> print f.read(24)
>>
> 
> ## new test...
> 
> f = FTPFile("HOSTNAME", "FILENAME")
> 
> while 1:
>     data = f.read(24)
>     if not data:
>         break
>     print data,
> 
> 
>>
>> I open the ftp connection inside the read method as it caused an error 
>> (on the second call to read) when I opened it in  __init__ ???
>>
>> HTH
>> Martin
>>
>>