Re: tasks and protected types

[Jacob Sparre Andersen <sparre@hugin.crs4.it>]

Fabio de Francesco wrote:
> Jacob Sparre Andersen wrote:
> > Fabio de Francesco wrote:

> > And then I also prefer to keep the printing to a single protected
> > object.
> 
> Why? Could lines come out intermixed? Does it mean that it is always
> needed to protect every call to library functions and procedures? Do
> they use global variables?

They modify the global variable "Ada.Text_IO.Standard_Output".

> Why an error in using strings makes the program to behave as it was
> a deadlock?

Exceptions in tasks is un(?)fortunately not something I really
understand.  I don't think that it matters that it is something with
strings.  I think putting a "raise Some_Exception;" in the accept
block would give the same result.

If you will accept a guess: An exception is raised in the first accept
call.  This means that the D1 task terminates (they do that, when you
have exceptions), but without finishing the accept block.  This leaves
Manage hanging, waiting for D1 (which is dead) to finish its accept
block.

Greetings,

Jacob
-- 
"Three can keep a secret if two of them are dead."