[Python-Dev] Decimal data type issues

[Batista, Facundo]

[Ka-Ping Yee]

#- I agree with Tony.  Having both Decimal() and 
#- Decimal.from_string() work
#- in similar but subtly different ways seems likely to be 
#- misunderstood.

Decimal(string) works the way we want/need/desire.
Decimal.from_string(string) works the way the documentation specify.

I think we can only change the way the former works or the name of the
latter.


#- I also think his last suggestion could provide a nice, 
#- convenient solution
#- to the conversion-from-float issue, since it raises the same 
#- question (a
#- method named "Decimal.from_float" doesn't explain how or why 
#- it is different
#- from just constructing with a float).

You can NOT construct directly from a float. That's the difference.


#- So here's a more detailed suggestion.  Suppose s = '12345', 
#- f = 12.345,
#- the default context specifies a precision of 9 as given in 
#- the PEP, and
#- c is a context object with a precision of 6.
#- 
#- Then this:                      would yield this:
#- 
#- Decimal(s)                      Decimal((0, (1, 2, 3, 4, 5), 0))
#- ...
#- Decimal(s, context=c)           Decimal((0, (1, 2, 3, 4, 5, 0), -1))
#- ...
#- Decimal(f)                      Decimal((0, (1, 2, 3, 4, 5, 0, 0, 0, 0,
0,...
#- ...

The community agreed to not create directly from float. You have the
from_float() method instead.

Also, remember that the context doesn't affect the creation when you create
directly from string (only if you use from_string).  Your example means to
change the behaviour of the creation when creating directly from string? And
when create directly from int or long?


#- (Do I assume correctly that there will be context objects 
#- that wrap up
#- the precision and rounding mode, and there will be some sort 
#- of interface
#- for getting and setting the current context?)

Yes. You can get the context with getcontext() and then change it
attributes.

.	Facundo