"index" method only for mutable sequences??

[James Stroud]

C.L. wrote:
> I was looking for a function or method that would return the index to the first
> matching element in a list. Coming from a C++ STL background, I thought it might
> be called "find". My first stop was the Sequence Types page of the Library
> Reference (http://docs.python.org/lib/typesseq.html); it wasn't there. A search
> of the Library Reference's index seemed to confirm that the function did not
> exist. A little later I realized it might be called "index" instead. Voila.
> 
> My point is that the docs list and describe it as a method that only exists for
> MUTABLE sequences. Why only for mutables? The class of objects I would expect it
> to cover would be all ordered sequences, or, to phrase it a little more
> pointedly, anything that supports ordered INDEXing. My understanding is that
> dict's don't fall into that class of objects since their ordering is not
> documented or to be depended on. However, tuple's do support ordered indexing,
> so why don't tuple's have an index method?
> 
> P.S.: I know I haven't yet gotten an answer to my "why" question yet, but,
> assuming it's just an oversight or an example of design without the big picture
> in mind, an added benefit to fixing that oversight would be that the "index"
> method's documentation could be moved from the currently odd seeming location on
> the "Mutable Sequence Types" page to a place someone would look for it logically.
> 
> P.P.S.: As much as the elementary nature of my question would make it seem, this
> isn't my first day using Python. I've used it on and off for several years and I
> LOVE Python. It is only because of my love for the language that I question its
> ways, so please don't be overly defensive when I guess that the cause for this
> possible oversight is a lack of design.
> 
> Corey Lubin
> 
> 

The amount of typing wasted to defend design decisions such as this can 
boggle one's mind. Just use lists unless you have on overwhelming reason 
to do otherwise.

James