Re: Newbie question -- dereferencing access

Tim Rowe wrote:
Tim Rowe wrote:

Georg Bauhaus wrote:

Tim Rowe schrieb:

Alex R. Mosteo wrote:


But I can't put an unconstrained type into a record.


Have you seen Bounded_String (and Unbounded_String)?


Not yet, but I'll go and explore...



Ok, I've seen it now! Am I correct that the statement in the
spec that "No storage associated with an Unbounded_String object
shall be lost upon assignment or scope exit" means somebody else
has done all the work of handling the underlying access types
and I don't need to worry?

That is the intent, yes, as Pascal Obry already replied.

I note that it does have a free method, but presumably that's just for early release before it goes out of scope.

There could be such a method for Unbounded_String, but actually the Free procedure in Ada.Strings.Unbounded works on the type String_Access, which is just an access to an ordinary fixed-length String (assumed to be dynamically allocated if Free is used).

I have often used Unbounded_String but never that procedure Free or the String_Access type. They have no public connection to Unbounded_String; probably they are declared in Ada.Strings.Unbounded just because the private implementations of Unbounded_String commonly use them, and the language designers thought that they might as well be public in case somebody finds them useful for other purposes.

If I wanted to discard the storage of an Unbounded_String variable S at some point in the program, before S goes out of scope, I would assign S := Null_Unbounded_String. This is likely to discard the storage for S, but I think the Ada standard does not guarantee that it happens at the assignment; it might happen later.

--
Niklas Holsti
Tidorum Ltd
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