I wrote:
(a) What's the syntax for changing the context? I'd think we'd want a "pushDecimalContext()" and "popDecimalContext()" sort of approach, since most well-behaved routines will want to restore their caller's context.
Facundo Batista replies:
You can save a copy of the context in a variable and then restore it. No stack.
Imagine the following senario. I write some code which uses Decimal, and which sets the context to get the desired rounding behavior. Somewhere in my code I call a routine written by somebody else... perhaps some library code... which also does some calculations using Decimal. It would be a major pain if every time I called that library code it changed the context. I'd have to keep setting the context back after each and every call to the library code. A well-behaved library will not require me to go through these contortions, so after it does its work it will set the context back to what it was when I called it. It seems to me that in almost all situations where one changes the context, one will also want to restore it later. If so, then it seems perverse to tell every user that they must capture and store the old context someplace and restore it later. Why not make the best practice be the *obvious* idiom by providing matched pushContext() and popContext() functions as the normal way of setting the context. Of course, one could choose to call pushContext() without a matching popContext(), or call popContext() repeatedly until the stack is empty (some exception is raised), but if the best behavior is the easy behavior then most people will use it. And if that didn't convince you, then go ahead... I think it's only a minor detail. -- Michael Chermside