Getting TYPE on Generic

[lrix]

How does one get the TYPE [K] of a Generic without creating an object of that type? I need to base creation of KL_COMPARATOR [K], where K = type of the key.

[lrix]

Obviously, my code example (above) does not work because I cannot do a non-object call on generating_type. I have to think that such a test to determine precisely what [K] is can be done. :-)

[lrix]

Nevermind ...

[Gachoud Philippe]

as far as I remember ({K}).generating_type, see ANY and TYPE class for more details and functions

On Thu, Mar 25, 2021 at 12:07 PM lrix <lr...@jinny.com> wrote:

How does one get the TYPE [K] of a Generic without creating an object of that type? I need to base creation of KL_COMPARATOR [K], where K = type of the key.

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[lrix]

So, the solution turned out to be writing a very generic KL_COMPARATOR that could be sufficient for type-variants for K

https://github.com/ljr1981/base_collections

[Ulrich Windl]

Hi!

I'm not good in Java, but I think the major difference is that in Java you make a class comparable by adding and implementing the comparator interface, while in Eiffel you inherit COMPARABLE.

Regards,
Ulrich

>>> lrix <lr...@jinny.com> schrieb am 25.03.2021 um 16:17 in Nachricht
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[Rosivaldo Fernandes Alves]

Hi Irix.

I hope I'm not getting wrong your question, but I have managed to get
the type of a generic via querying {TYPE}.generic_parameter_type
feature. Below is the code of a function I've written where I use such a
facility.

Hope this helps.

Best regards,

Rosivaldo.

result_type (a_new_instance: FUNCTION [detachable separate ANY]): TYPE
[detachable ANY]
-- Result type of the function accessed via `a_new_instance' agent
local
l_new_instance_type: TYPE [detachable ANY]
do
l_new_instance_type := a_new_instance.generating_type
check
large_enough: l_new_instance_type.generic_parameter_count >= 1 --
FUNCTION [detachable separate ANY] has generic parameters.
small_enough: l_new_instance_type.generic_parameter_count <=
l_new_instance_type.generic_parameter_count -- By definition
end
Result := l_new_instance_type.generic_parameter_type
(l_new_instance_type.generic_parameter_count)
end

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