Re: Need a way to convert a constant to a variable

["Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>]

On 08/05/2017 03:41 PM, Victor Porton wrote:
> 
> Write a function with an "in" indefinite holder with a string, return
> chars_ptr corresponding to the string.

Your requirements are for an indefinite holder with a string, but your attempted 
solution is for an indefinite holder with a char_array. I will assume you meant 
an indefinite holder with a char_array.

> It looks like there is no solution of this in Ada 2012 :-(

with Ada.Containers.Indefinite_Holders;
with Interfaces.C.Strings;

package Conv is
    package C_Str_Holders is new Ada.Containers.Indefinite_Holders
       (Element_Type => Interfaces.C.Char_Array, "=" => Interfaces.C."=");

    function To_Chars_Ptr (Item : C_Str_Holders.Holder)
                        return Interfaces.C.Strings.Chars_Ptr is
       (Interfaces.C.Strings.New_Char_Array (Item.Element) );
end Conv;

This compiles fine, so clearly there is a way to do this without a language change.

-- 
Jeff Carter
"He didn't get that nose from playing ping-pong."
Never Give a Sucker an Even Break
110

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