Re: Garbage Collection in Ada

[rogoff@sccm.Stanford.EDU (Brian Rogoff)]

jsa@alexandria (Jon S Anthony) writes:
   Richard Riehle <rriehle@nunic.nu.edu> writes:
   > While it is true that Root_Storage_Pool is derived
   > from Ada.Finalization.Limited_Controlled, this should not be
   > a particular hardship when control over the storage pool,
   > and automatic garbage collection are essential to a given design.

   The keys are being able to

   a) tie an access type to a pool
   b) define a type which cannot be allocated except by user defined 
      constructor (limited type with unknown discriminants).  This 
      gurantees that a) is the only access type a client can use for the type.

   c) ability to redefine _new_ for the pool

   to a much lesser extent: 

   d) ability to redefine manual deallocation for pool.

   Finalization for the pool could also be useful (though only in special
   cases)

I mentioned that the ODMG Ada 95 binding paper, which I can no longer find on 
the web, had a discussion of storage pools, and suggested that a very similar 
feature be designed which was like Storage_Pools except that it supported 
user definable dereferencing and rereferencing of access types. This was 
used for persistence and GC.

-- Brian