Your list of ways that Decimal's model is better is an excellent list
Thanks. Add one more. The specs, the docs, the tutorial, and docstrings are chock full of extensive examples. Those examples include NaNs and Infinities. If the traps are all turned off by default, then the examples fail. That would suck. I've spent weeks trying making sure the module integrates well with the rest of Python. To make the API choices as informed as possible, I built some apps, wrote the docs (incl. docstrings, tutorial, and whatsnew), communicated with Cowlishaw, communicated with the other module authors, and read the after-the-fact usability reviews on Java's big decimal package. So, please, try out the module as-is and share the results of your experience.
So in the end, we're talking about what we want to do for people who choose NOT to read the docs.
People have been fond of quoting Tim lately. I think either he or Guido said that they are not persuaded by arguments that people are not bright enough to get concepts like Infinity or NaN: >>> Decimal(1) / Decimal(0) Decimal("Infinity") Not nearly as hard as descriptors, Unicode, half-open intervals, etc ;-)
But if we left traps OFF then these foolish people might see that their program had run to completion and then accept the results without even realizing that there was a way to check for signals.
I'd like to think that wise people choose decimals over floats ;-) More seriously, non-casual users of decimal *will* have to grapple with the concept of contexts. It is intrinsic to what the module is about. It's not difficult, but it can't be avoided. To that end, I introduced contexts right away in tutorial and in the quick-start section of the docs. Raymond P.S. Your reply address doesn't work for me.