[Patches] [ python-Patches-553277 ] Little ftplib bug

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Patches item #553277, was opened at 2002-05-07 16:02
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Category: Library (Lib)
Group: Python 2.2.x
Status: Open
Resolution: None
Priority: 5
Submitted By: Geert Jansen (geertj)
Assigned to: Nobody/Anonymous (nobody)
Summary: Little ftplib bug

Initial Comment:
There seem to be a little bug in FTP.retrlines in the 
module ftplib in the standard library. In this 
function, the default value for the "callback" 
parameter is None. The absence of a callback parameter 
is tested in the body if the function with "if not 
callback:". 

This gives problems in real-life when you're using a 
callable container class as the callback function. 
When the container is empty (__len__  returns 0), the 
test "if not callback:" is true and a default callback 
is used instead of the user supplied one.

The fix is to change the test "if not callback" to "if 
callback is None:". One-line patch attached.

Greetings,
Geert Jansen

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