TEDBQuery and TEDBTable are both documented as deriving from TDataSet, but the actual class inheritance chain appears to be broken at
TEDBDataSet and TEDBDBDataSet. Point being I can't a TEDBTable or TEDBQuery object of my choosing to a TDataSet pointer and navigate it.

Is there a reasonable workaround to this problem?

Jeff

I've just tried

TDataSet(Users).First; and TDataSet(Users).Last;

with no problem. Users is a TEDBTable.

What are you trying?

Roy Lambert [Team Elevate]

Jeff.

<< TEDBQuery and TEDBTable are both documented as deriving from TDataSet,
but the actual class inheritance chain appears to be broken at TEDBDataSet
and TEDBDBDataSet. Point being I can't a TEDBTable or TEDBQuery object of my
choosing to a TDataSet pointer and navigate it. >>

You most certainly can.  What is giving you the impression that the
components are not descended from TDataSet ?

--
Tim Young
Elevate Software
www.elevatesoft.com

class foo : public TDataSet
{
   foo(TDataSet *);
};

class bar : public foo
{
   bar(TDataSet *);
}

foo::foo(TDataSet *ds)
{
}

bar::bar(TDataSet *ds) : foo(ds)
{
}

I get [BCC32 Error] bar.cpp(17): E2285 Could not find a match for 'foo::foo(TEDBTable *)'

It doesn't appear to recognize that TEDBTable inherits from TDataSet and so doesn't find a match. When I try to view header declarations up the
chain, I wind up staring at the end of a file rather than the declaration for TEDBDBDataSet. I'll look into the workaround mentioned above and see
if it provides me with an alternative.

It looks like it's just in the constructor where matching up the tree something is off. Other than that, casting appears to work properly so I can
work with this, and if I've made some grievous error in the class inheritance or namespaces it'll probably come to me when I'd rather be
concentrating on something else.

Jeff,

<< I get [BCC32 Error] bar.cpp(17): E2285 Could not find a match for
'foo::foo(TEDBTable *)'

It doesn't appear to recognize that TEDBTable inherits from TDataSet and so
doesn't find a match. >>

You're trying to cast a *descendant* of TDataSet to a TEDBTable, which is
not possible since they do not share the same single inheritance path.  You
can only cast objects to a different class type if that class type is
present in the direct ancestry of the object being casted.

For example:

TDataSet -> TEDBTable = Good
TEDBTable -> TDataSet = Good
TEDBTable -> TTable = Bad
TEDBTable -> TADOTable = Bad

--
Tim Young
Elevate Software
www.elevatesoft.com