List of Dictionaries

[Russell E. Owen]

In article <14dc40e2.0203071559.5e3d4550 at posting.google.com>,
 lenny_self at hotmail.com (Lenny Self) wrote:

>I am having a problem I was hoping someone might be able to help me
>with.  I am attempting to append several dictionaries to a list for
>further processing, however I am seeing some rather odd behavior.
>
>When I add the first dictionary element to the list all is well.  When
>I add the second element to the list both the first and second element
>reference the second dictionary that was added.  The behavior
>continues whenever I add an element.  So, if I add, say 50
>dictionaries, all of the listes elements reference the last dictionary
>I added....

My guess is that mail.getData() is returning a reference to a dictionary 
it uses internally, rather than returning a copy of that dictionary. 
Hence you end up with multiple references to the same dictionary.

Usually, whenever I return a list, dictionary or other mutable 
application, I return a copy to avoid this problem.(In some situations 
this is may be appropriate or impractical, but that usually indicates 
poor class design - the contents of an object should usually remain 
private).

If you cannot or prefer not to change the application returning the 
data, then change the calling program to make a copy of the dicationary 
before using it.

-- Russell
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