Re: Object-relational impedence

On 14 Mar, 10:43, "Dmitry A. Kazakov" <mail..._at_dmitry-kazakov.de> wrote:
> On Thu, 13 Mar 2008 22:17:40 -0700 (PDT), frebe wrote:
> > On 13 Mar, 18:40, Robert Martin <uncle..._at_objectmentor.com> wrote:
> >> The real point of that remark was that the user of a tool is at a
> >> higher level of abstraction than the tool itself.  SQL is a tool.  ORMs
> >> are tools that use SQL to get their job done, just like compilers use
> >> assembly to get their job done.  In that sense ORMs live at a higher
> >> level of abstraction than SQL.
>
> > Lets have an example: There are many "compiler" products translating
> > from a high-level language like ADA to a low-level language like C,
> > instead of translating to machine code directly. What if someone wrote
> > a "compiler" translating C source code to ADA source code, would that
> > make C more high level than ADA? Hardly? The existance of a product
> > translating from language A to language B doesn't say anything about
> > the levels of A and B.
>
> Right. What does it, is the difficulty of designing such a compiler.
> Clearly within the set of Turing-complete languages you could translate
> from whatever language to any other. But, while translation from Ada to C
> is considerably difficult (mainly because C is ill-defined), a good
> translation from C to Ada is almost impossible.

That's why the OO camp has such problems with making a good ORM. If SQL would have been low-level, compared to the network model, the task would have been much easier.

//frebe Received on Fri Mar 14 2008 - 14:33:45 CET