OpenEuphoria

Structures are NOT a new datatype

• Posted by Ralf Nieuwenhuijsen <nieuwen at XS4ALL.NL> Jan 31, 1999
• 435 views

First of all, structures are already implemented. We just call them
sequences now are able to change their *structure* all the time. But I dont
want to change the structure. This involves a long type check, which checks
the lengh and type and possibly the sub-type of every element in the
sequence. This all to avoid some silly mistakes. Result: nobody writes such
type checks, and just debugs through print statements and the tracer, since
the actual origin of the problem has not been found. (a wrong value in a
type, normally, would show up much later in the program, totally unrelated
to where the 'bug' is, while with a type check, the bug is caught where it
occurs, rather than where it first brakes your code ). So what _do_ I do
want ?

Two things:

    * constants declared local to a sequence for slicing only.
    * the ability to define a structure at once, without the need of
building it up using dynamic routines and to assign a type to each element
of a sequence. So, not a new language element. But a new feature. A new
syntax rather. A new way of doing something we already can. Why ? More
readable. Better maintainable.

The same goes for arrays. They already exist in the form of sequences. I
just want the interpreter to be so smart to read this:

type byte (integer x)
    return x >= 0 and x < 256
end type

byte namespace[20] = ' '

..... to read that as...

type specific_type_for_ns (sequence s)
    if length(s) != 20 then
        return 0
    end if
    for index = 1 to 20 do
        if not byte (s[index]) then
            return 0
        end if
    end for
end type

specific_type_for_ns ns
ns = repeat (' ', 20)

----- Well, let me guess, you purist Euphorians......

You thought the second example was more readable and can be much better
optimized!

Why is there a repeat function in Euphoria, while you could just do:

    sequence ms
    ms = ""
    for index = 1 to 20
        ms = append(ms, ' ')
    end for

Well, for two reasons:

    - better readable (repeat (' ', 20) is much more logical)
    - it can be optimized enormously.

And for the same two reasons I want arrays & structures, yet now these
arguments are considered insufficent!

Or is the real difference, that C does not have a repeat statement ?
What the hell does C got to do with the discussion anyway ?

Ralf