all() is slow?

[Steven D'Aprano]

On Thu, 10 Nov 2011 15:37:05 -0500, Devin Jeanpierre wrote:

>> '--' not being allowed for a name has *nothing* to do with exec, and
>> everything to do with `--` not being a valid Python identifier.
> 
> The only reason valid python identifiers come into it at all is because
> they get pasted into a string where identifiers would go, and that
> string is passed to exec().

That is patently untrue. If you were implementing namedtuple without 
exec, you would still (or at least you *should*) prevent the user from 
passing invalid identifiers as attribute names. What's the point of 
allowing attribute names you can't actually *use* as attribute names?

You could remove the validation, allowing users to pass invalid field 
names, but that would be a lousy API. If you want field names that aren't 
valid identifiers, the right solution is a dict, not attributes.

Here's a re-implementation using a metaclass:

http://pastebin.com/AkG1gbGC

and a diff from the Python bug tracker removing exec from namedtuple:

http://bugs.python.org/file11608/new_namedtuples.diff


You will notice both of them keep the field name validation.


-- 
Steven