Re: Charles container library usage examples

[David Trudgett <wpower@zeta.org.au.nospamplease>]

"Matthew Heaney" <mheaney@on2.com> writes:

> Yes, you need to make two instantiations: one to create a list of
> integers, and another to create a map of lists.
>
> If your list always comprises two elements, then you can use a
> constrained array instead.  Something like:
>
>   type Integer_Array is array (Positive range <>) of Integer;
>   subtype Integer_Array_Subtype is Integer_Array (1 .. 2);
>
> or the simpler:
>
>    type Integer_Array is (1 .. 2) of Integer;

Yes, thanks. I used something similar. Using a list didn't give me
anything for the extra effort involved.



>
> Then you can use that as the generic actual Element_Type in the
> instantiation of the map (and hence get rid of the list instantiation
> entirely).

Good idea! ;-) :-)


> If you're using an Ada 95 compiler, then you'll have to instantiate the
> container packages at "library level," for subtle reasons.  (Things are
> a lot simpler in Ada 05, and you'll be able to instantiate the
> containers in a local scope.)

Yes, that will be a lot more convenient.


>> When I tried to instantiate a hashed map, it seemed to want me to
>> supply a hash function.
>
> Then just use an ordered map.  Subtype Integer has a built-in less-than
> operator, so you don't need anything extra to instantiate the ordered
> map.

Yep. I used the ordered map instead of the hashed map. By the way,
does Charles have general purpose hashing functions, or do you need to
roll your own? I thought I saw a string hash function in PragmARC. Is
it suitable for use in Charles?


> (Ada and C++ are low-level, systems programming languages, so we
> typically have to think about these things.)

Yep.


David



-- 

David Trudgett
http://www.zeta.org.au/~wpower/

Who would Jesus bomb?