Re: Seed7 Release 2008-02-17

On 18 Feb., 17:42, "Aaron Gray" <ang.use...@[EMAIL PROTECTED]
> wrote:
> "Aaron Gray" <ang.use...@[EMAIL PROTECTED]
> wrote in message
>
> news:61t25sF2003j0U1@[EMAIL PROTECTED]
>
> >> - The manual was changed to mention that the 'in' parameter of arrays
> >>  and structs is a reference ('ref') parameter.
>
> > Is that overridable or is the a const modifier ?
>
> Sorry what I ment to type was :-
>
>     Is that overridable or is there a const modifier ?

It is overridable by using 'val' of 'ref' parameters.
Instead of:

  const func integer: test1 (in array string: anArray) is
    return length(anArray);

it is possible to write:

  const func integer: test2 (ref array string: anArray) is
    return length(anArray);

which is normally equivalent to the test1 example.
If you want a value parameter for an array you can write:

  const func integer: test3 (val array string: anArray) is
    return length(anArray);

I know that it is stupid to copy an array just to return it's
length, but it is possible. There is also a possibility to
override the meaning of an 'in' parameter by declaring a
subtype as in the following example program:

  $ include "seed7_05.s7i";

  const type: myArray is subtype array string;

  IN_PARAM_IS_VALUE(myArray);

  const func integer: test4 (val myArray: anArray) is
    return length(anArray);

  const proc: main is func
    local
      var myArray: anArray is 100 times "x";
    begin
      writeln(test3(anArray));
    end func;

That 'in' parameters for arrays are by reference ('ref') is
defined in the "seed7_05.s7i" library.
Since most of Seed7 is defined in "seed7_05.s7i" the
meaning of 'in' parameters and many other things can be
changed there, but in most cases this is not desirable.

To answer the second part of your question:

  is there a const modifier ?

is easier. The formal 'in', 'val' and 'ref' parameters are
already const. Therefore a const modifier is not needed.

For variable parameters see my previous mail about 'inout'
and 'in var' parameters.

I hope this answers your question.

Greetings Thomas Mertes

Seed7 Homepage:  http://seed7.sourceforge.net
Seed7 - The extensible programming language: User defined statements
and operators, abstract data types, templates without special
syntax, OO with interfaces and multiple dispatch.