Re: [Liberty-eiffel] Array with integers. real and strings

[Paolo Redaelli]

Il 27/03/2016 21:23, Germán Arias ha scritto:
> Hi,
>
> Is posible have an array/native array with integers, real and strings? I
> try with ARRAY[ANY], but don't work. Or maybe a tuple with different
> types? The problem is that I don't know. beforehand, the order of the
> arguments. This is, something it can be: integer, string, integer, .....
> and others: string. string, real,... And I need pass it to a C
> function. 
What kind of problem are you trying to solve?
I don't want to prejudge but this kind of issues raise when you try to
solve a problem in Eiffel in a mostly unEiffellish way.

INTEGERs and REAL are expanded classes, while string-like classes are
reference string.
All the heirs of ABSTRACT_STRING are reference classes actually. In fact
it is usually better to use ABSTRACT_STRING instead of STRING whenever
possible as queries arguments since you may that way provide a ROPE, a
STRING, a FIXED_STRING, a LAZY_STRING and so on....
It is not possible to mix expanded and reference classes in the same
container as they don't have a common inherited anchestor: all expanded
classes insert the features of ANY but they don't conform to ANY.
You may use VARIANT and TYPED_VARIANT to achieve this but that's somehow
clumsy.
GObject had the same issues and solved them having variant-like,
reference classes that acts like a union.

You may take a look at the quick hack I wrote in this branch
https://github.com/tybor/Liberty/tree/variant and in particular
https://github.com/tybor/Liberty/blob/variant/tutorial/variant_usage.e
I've put into a ephemeral branch because of the change I made to
TYPED_VARIANT.out which may not be wanted as a language-wide change.