Question

I want to create a task type (for example the a task type called “computer”) with some task entries in Ada. I want to create a task entry with an input parameter of type “is access all computer”, i.e. a pointer to the task type. Is this at all possible?

I tried to do something like this:

task type computer;
type computer_ptr is access all computer;    
task type computer is
  entry init(a: computer_ptr);
end computer;

This was suggested here. Unfortunately, this doesn’t work: GNAT says that the declarations of “computer” conflict.

Can anyone think of a way to achieve what I want to do?

Answer 1

By using task type computer;, you declare a task type computer with no entries at all. Afterwards you declare another task type with the same name.

If you want to “forward-declare” the task type (as needed for the access type), you should just write type computer; like for any other type. This is a incomplete type and can be completed by a task type declaration.

So your example should look like this:

type computer;
type computer_ptr is access all computer;
task type computer is
   entry init (a: computer_ptr);
end computer;