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From: Tobias Schwinger (tschwinger_at_[hidden])
Date: 2005-06-30 06:49:29

John Maddock wrote:
>>OK, here is my current top-candidate:
>> When classifying types it is often necessary to match against
>> several variations of one aspect.
>> There are special variations which make this possible. These are called
>> *abstract*.
>> The most important case is to match any variation; that is, to ignore
>> that aspect in the context of type classification. Because of this,
>>aspect has at
>> least one abstract variation named "unspecified_" plus the aspect name.

;-( - I knew this would happen... I accidently hit the "Send"-button before the
post was finished...

> That one also makes sense to me, I'm still not sure that "abstract" is the
> right word though :-)
> Explanation: to me if something is "abstract" then you need to add something
> to it, extend it in some way to make it concrete. What you're doing is

Interesting... This is exactly why I came up with this term in the first place:

An abstract variation of an aspect does not concretely describe the aspect
of the kind of type. It describes it, well, in an /abstract/ way:

Looking at classification, analog to pointer declaration, we constrain a (kind of)
type by specifying a special (kind of) type that only describes a category (but
nothing concrete).

Type synthesis is in some ways similar to a constructor call: actually we can't
create an "unspecified decorated" function type - we can only create an
undecorated or (member-)pointer-decorated or reference-decorated function type. So
there /is/ the kind of extension you describe, although implicitly done by a
default mechanism.

"Abstract" let's the user intuitively suspect something like an "external tree
structure" (i.e. only leafes carry user data), that's why I like it.

> combining several concrete definitions to form a non-specific union of some
> kind. So a quick trip to suggests: "composite", "compound" or
> "mixed" as possible names, do any of these work for you?

I'm not convinced, yet. Maybe I'm having difficulties to fully understand you. Can
you perhaps try to clarify what makes "abstract" unsuitable in your opinion?



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