Re: class wide iterable (and indexable)

["Randy Brukardt" <randy@rrsoftware.com>]

"Shark8" <onewingedshark@gmail.com> wrote in message 
news:95f6a9b0-adc6-4044-8ff8-f0820612aeea@googlegroups.com...
> On Thursday, January 3, 2019 at 1:52:50 AM UTC-7, Simon Wright wrote:
>>
>>
>> The Ada 95 Booch Components[4] follow this model. One reason they
>> weren't taken as a model for Ada.Containers was that the model requires
>> multiple levels of generic instantiation of child packages: for example,
>> to make an unbounded map from Unbounded_String to Unbounded_String
>> requires
>>
>>    with Ada.Strings.Unbounded;
>>    with BC.Containers.Maps.Unbounded;
>>    with BC.Support.Standard_Storage;
>>
>>    package Configuration_Demo_Support is
>>
>>       package Abstract_String_Containers is new BC.Containers
>>         (Item => Ada.Strings.Unbounded.Unbounded_String,
>>          "=" => Ada.Strings.Unbounded."=");
>>
>>       package Abstract_String_Maps
>>       is new Abstract_String_Containers.Maps
>>         (Key => Ada.Strings.Unbounded.Unbounded_String,
>>          "=" => Ada.Strings.Unbounded."=");
> True; but the Automatic Instantiation AI would relieve a lot of the hassle 
> here --  
> http://www.ada-auth.org/cgi-bin/cvsweb.cgi/ai12s/ai12-0268-1.txt?rev=1.2

The AI you refer to is only about formal packages, while the above doesn't 
have any formal packages so I fail to see how it would help.

A more general automatic instantiation mechanism was also proposed in 
AI12-0215-1. But that one is a dead-body issue for me (at least as 
proposed). Ada gives specific places where every declaration occurs 
(statically) and is elaborated (dynamically). AI12-0215-1 throws that 
property completely away, harming analyzability, readability, and 
understandability -- it would be much like saying that there's no neeed to 
declare objects before using them because the compiler can figure out what 
was intended. Bah humbug. :-)

                            Randy.