Re: [Axiom-developer] Spad and its object model

[Gabriel Dos Reis]

Stephen Wilson <address@hidden> writes:

| Gabriel Dos Reis <address@hidden> writes:
| 
| > On Mon, 11 Jun 2007, Stephen Wilson wrote:
| > 
| > | > I guess what I trying to get at is what are the benefits of those 
| > | > additional indirections over simple, hash table representation.
| > | 
| > | I would imagine that the vast number of lookups would suffice with an
| > | integer index.  Tiny fraction would require higher level keys. 
| > 
| > Lookup with integer index is OK when you have all information at the
| > same place and at the same time and have a way to enforce its
| > semantics.  Currently, Spad is such that one needs to have all
| > the information when constructing the vtable but there is no means
| > to enforce consistency.  Going to a world with "extend" makes
| > the problem even more accute.
| 
| If the vtable can be interrogated with a variety of keys, allowing
| useful mapping of elements, I dont see how a hash is any more
| flexible.  Perhaps you could provide an example?

Did I say "more flexible"?

When you have an array and you index it with value 2, what does "2"
means? 

[...]

| > | I dont think of the integer index as having anything to do with the
| > | order of declarations.
| > 
| > Please elaborate on its semantics then.
| 
| Nothing fancy. Its just a key, no more, no less.

Sorry, "nothing fancy" is not an executable semantics.

-- Gaby