Subj : Re: Polymorphism sucks [Was: Paradigms which way to go?]
To   : comp.programming,comp.object
From : topmind
Date : Thu Jun 30 2005 07:17 pm

>
> >>> [...tree snipped...]

It got what it deserves :-)

> >>>
> >>> Most people would produce a fiarly similar hierarchy without even
> >>> seeing this one.
> >>
> >> LOL!  You mean to say it is so naturally tree-shaped that most people
> >> would naturally produce a tree?
> >
> > I have agreed that *people* naturally relate to trees.
>
> First, why do you think that is?

That is a very good question that I cannot fully answer. Ask the chief
engineer(s) of the brain.

I suspect in part it is because trees can be well-represented visually
such that the primary pattern is easy to discern. I say "primary"
because trees often visually over-emphasis one or few factors at the
expense of others.

Sets can be used for visual inspection also, but it takes some training
and experience to get comfortable with them. Part of this is because
one must learn how to "query" sets from different perspectives. There
generally is no one right view (at least not on 2D displays) that
readily shows the pattern(s). One has to get comfortable with query
tools and techniques.

>
> Second, *people* create programs.  Therefore, obviously, the tree must be
> one of the natural models.


Do you mean natural to the human mind or natural to the universe such
that all intelligent space aliens will also dig them?

Being natural does not necessarily mean "good". For example, it is
natural for humans to like the taste of sugar, fats, and fiber-free
starch. However, too much of these often make us unhealthy.

Similarly, I agree that trees provide a kind of *instant
gratification*. It is the longer-term or up-scaling where they tend to
bite back. Thus, sets are for the more educated, enlightened mind in my
opinion. Sets are health-food for software design.


>
> > Thus, they tend to produce algorithms that have a tree-shaped division
> > of tasks. It is not that tasks are inherently are tree-shaped, it is
> > that people are more comfortable using trees to describe them.
>
> And why do you think that is if not because hierarchical structure is
> both natural and *useful*.


See the note above about instant gratification.

> (Things that are not useful do not tend to
> survive that long.)

Maybe tree-lovers will become extinct in a few thousand years, to
be replaced by the superior HomoSETius :-)


>
> > However, on a larger scale algorithms are not pure trees because
> > usually named tasks (subroutines) eventually come in to play as we
> > scale up. Subroutines break the tree because they are cross-branch
> > links.
>
> First, as I've already pointed out, cross-branch links don't make a
> tree not a tree.  They just make it not certain types of trees.

"Type of tree"? Please clarify. If you print out the code on a big
sheet of paper and draw the lines between the subroutine references,
you will see that it is *not* a tree.

Now, *any* graph can indeed be represented as a tree if you are willing
to display inter-branch references as duplicate nodes, which is what
the multiple subroutine calls essentially are.

>
> Second, you don't really algorithm, you mean program.  Algorithms
> typically ARE very hierarchal ever since structured programming was
> invented.  Smaller blocks within larger blocks, just about every
> algorithm is structured that way.


On a small scale, yes. On a bigger scale it is not hierarchical, per
above. Many programs are generally hundreds of small trees joined by
lots of references that bust tree-ness. Picture drawing hundreds of
small trees randomly scattered on a large piece of paper. Now randomly
draw thousands of lines between various nodes of the different trees to
either the same given tree or other trees.  A big bowl of spaghetti
mixed with broccoli! Quite tasty and healthy to boot.


>
> > IOW, on a small scale or *informal* discussions (which is what the
> > above is), trees are a decent useful lie.
>
> You can label them a "lie" if you like, but they appear to reflect the
> truth of very many situations to me.

Well, every abstraction is probably a lie to some extent. Some are just
better lies than others. It is only a "truth" if you constantly
refactor them for each new combination that does not cleanly fit a
tree, or live with duplicate nodes.

>
> Clearly most of the human race would seem to agree, since you admit
> that "most people would naturally produce a tree."

Because most people are naive and go with instant gratification and/or
the comfortable. Sets are admittedly not immediately comfortable, but
they allow one to shift up a level of complexity and change management.
Enlightenment comes with a price. That's life.

-T-

.