On Feb 27, 2010, at 3:14 AM, Florent Hivert wrote:
Hi Robert,
In order to sanitize the behavior of objects, parents and elements
in
sage,
I'm about to add some tests to the framework. I think they are all
reasonable
but I may be asking to much. Please comment about the following:
1 - Any SageObject must have an equality methods such that
self == self and self != None
2 - Element construction should be idempotent. More precisely, for
any
element e within parent P, the equality P(e) == e must hold.
This is for example needed by the constructor of many Parent
with a
base
ring, such as matrices.
Elements of real interval fields don't satisfy the above two
constraints
(the notion of equality for intervals being that every element of
the first
interval is equal to every element in the second).
You get the point. As far as I understand a RIF only return True if
the
interval are reduced to a single point. Is it right ? It would be
better to
return a special value like Unknown than False. But that's another
question...
Anyway, I'm strongly info favor of giving 1- and 2- a general rule
with an
explicit exception for RIF. As I said, the test framework allows such
exceptions. Is there an agreement on
* Making 1- and 2- below a general rule
1 - Any SageObject must have an equality methods such that
self == self and self != None
2 - Element construction should be idempotent. More precisely, for
any
element e within parent P, the equality P(e) == e must hold.
* Making explicit exception for particular cases such as RIF.
I certainly agree that 1-2 should be the general rule, I was just
pointing out an exception. I like the idea of returning an Unknown
object on RIF comparisons as well.
- Robert
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