invert or reverse a string... warning this is a rant

[James Stroud]

Fredrik Lundh wrote:
> James Stroud wrote:
> 
>  > without requiring an iterator
> 
> can we perhaps invent some more arbitrary constraints while we're at it?
> 
> </F>
> 

I guess while I'm at it, this thread wouldn't have so much steam were 
these idioms seemingly unpythonic:

       "".join(reverse(x))
       alist[::-1]

The latter, while more terse than alist.reversed(), is unnatural and 
ugly compared to the general elegance of other constructs in python. 
Were this not the case, beginners and intermediate programmers alike 
would not have such trouble remembering it. In fact, the latter's exact 
behavior, if I remember correctly, spawned a thread of its own with much 
speculation as to the exact meaning of the documentation and whether the 
API conformed to this inferred meaning. I'll attempt to provide a link 
to the thread if anyone takes me to task on this.

I'm sure many life-long programmers will claim that they have never 
created a reverse copy of a data structure for production code, but why 
is it that so many jump to the fore to point out that alist[::-1] is how 
one produces a reverse copy of a list, or that a string can be reversed 
with reversed, join, and an instance of another string (did I leave 
something out?)?

But why do so many beginning programmers ask how one might produce a 
reverse data structure in python? Perhaps they are just ignorant fools 
who don't know that creating a reverse copy of a data structure can be 
proven to be a useless operation if only they would stop trying to write 
code and begin to write formal proofs. Perhaps their professors are to 
blame, unreasonably asking them to write actual code before memorizing 
all three+ volumes of Knuth. I'm sure the proof is in there somewhere.

But maybe it is not the purpose of a poweful language like python to be 
used as a teaching language. Maybe python should be reserved for use 
only by those who have been desensitized to its idiosyncracies, 
inconsistencies, and idiomatic workarounds.

James

-- 
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095

http://www.jamesstroud.com/