Easy immutability in python?

[Terry Hancock]

Whoops I forgot to list the reference.
Also, I just finished reading the old thread, so I see some
damage-control may be needed.

On Sat, 4 Mar 2006 11:52:59 -0600
Terry Hancock <hancock at anansispaceworks.com> wrote:
> [1]
> http://news.hping.org/comp.lang.python.archive/28916.html

And more specifically, I'm referring to Alex Martelli's
reply:

http://news.hping.org/comp.lang.python.archive/28966.html

[Vain attempt to co-opt a flame-war follows]

And having seen that that discussion largely devolved into a
rant about why "you shouldn't do that", can we PLEASE
restrict this thread to the *how*?

My use case is quite similar to Ben's enumeration type. In
both cases, assigning attributes to the objects is
NONSENSICAL and possibly UNWISE.  Any attempt to do so is
almost certainly a bug in your code if you are using my
module -- and it happens to be one I want to make sure I
catch.  It is also true that the average person using my
code is not a blackbelt pythoneer, but rather a scripter who
needs/wants training wheels whenever it is practical to
provide them.

If you are REALLY sure you want mutability, you can always
subclass it.

If you think that code that handles prime numbers by marking
integer objects like so:

101.prime = True

is "just fine", and are not bothered that 101 is
mysteriously unclassified sometime after you've marked it
(because 100+1 is 101 == False), then we are not going to
see eye-to-eye, so let's not argue about it.

I also am not trying to alter the Python language. I am
trying to figure out how to most easily fix __setattr__ etc
to act immutably, *using* the existing features.

I can already do what I want with some 25-30 lines of code
repeated each time I need it, but I think it's dumb that
it's that complicated.

-- 
Terry Hancock (hancock at AnansiSpaceworks.com)
Anansi Spaceworks http://www.AnansiSpaceworks.com