Modes

Modes

[Andrew Carroll]

> On 10 Oct 2003 11:18:28 -0400, Stephen Leake wrote:
> >"Andrew Carroll" wrote:
> ...
> >Tagged types and full limited types are always passed by reference,
> >because it almost always matters for them.
> ...
I wish I had writen that.

There's another Andrew here.  Great name by the way!
I guess I'll start singing my emails different.
I did post some information about using pointers to strings and started the
Modes
topic.

So, to follow up.  I revisited all the classes I am working on.  Their not
really classes
now.  Just records.  I made them private and followed Cohen's form.  All
that work wasn't
really that informative.  It just re-highlighted some things that will take
some time to get used
to with Ada.

For instance if I had a record that contained a count (private record that
is) like

package x is
    type x_type is private;
    type xptr is access all x_type;
    function getcount(this: x_type)return Integer;

private
    type x_type is private record
        count: Integer := 0;
    end record;
end x;

If I want a method to get the count I have to pass in an instance of what I
want to
get the count from.  Like:
...
var: xptr;
num: integer;
var := new x_type;
num := getcount(var);
...

I come from C++, Java so that looks more like linear programming to me.
That is, without the dot notation like var.getCount();
Just something to get used to.

I got the "modes" covered now as well.  The only thing I noticed after I
changed some
stuff with modes and the records is that it seems to compile faster and run
slower.  Didn't
expect that but...what can I say?

So I'm working on the string stuff now.  I'm pretty sure you all knew this
but there is a
String_Access defined in Unbounded_String and in Gnat.OS_Lib.  What a
coinkidink.
Something else I didn't know "For parameter types unconstrained types are
allowed,
similar to passing int array[] in C. " (Ada-95: A guide for C and C++
programmers
by Simon Johnston)  So, if I have a function makeString(input: String)
return String then
I can pass in a string of most any size, then return it.  Don't know if this
is really helpfull yet.

Ohhh, by the way.  No one posted a list of the "rules of thumb" for Ada.
Here, I'll
repost my post:
>[snip]
>> The rule of thumb is: newer use pointers if there is an alternative.
>> So:
>[snip]
>>Thus another rule: if a pointer, then when possible anonymous:
>>    procedure Add (This: access X; Token: Unbounded_String);
>>       -- This will be a primitive subprogram of X
>>
>[snip]
>> The Ada way is not to create objects you do not need.
>Okay, so now we're getting to the information I want to know.
>The "rules of thumb" for the "Ada idiom".  Anyone got a list of
>"standardized rules of thumb for the Ada idiom"?

Well, take care all.

Andrew C.