From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Proposal: Auto-allocation of Indefinite Objects
Date: Sat, 4 Apr 2020 10:31:35 +0200
Date: 2020-04-04T10:31:35+02:00 [thread overview]
Message-ID: <r69gl7$1ntr$1@gioia.aioe.org> (raw)
In-Reply-To: 94a54092-a56f-4a99-aaec-08dd611c8fd8@googlegroups.com
On 2020-04-04 00:48, Stephen Davies wrote:
> It is the 3rd reason that initially got me thinking about this.
> It seems excessive to have two versions of packages just because
> one version can say "Node.Item := New_Item;" but the other has to say
> "Node.Item_Ptr := new Element_Type'(New_Item);".
This is another issue, IMO. The language should support interface
inheritance:
type Node_Item_Inteface is ...;
type Static_Node_Item is
new Node_Item_Inteface with record ...
type Dynamic_Node_Item is
new Node_Item_Inteface with access Some_Implementation;
Implementation of an interface per access type.
> It's probably not a good idea for auto-allocation to be the default
> behaviour, so I suggest something like:
>
> type Node_Type is record
> Item : new Element_Type;
> Prev : Node_Ptr_Type;
> Next : Node_Ptr_Type;
> end record;
>
> If Element_Type is a definite type in the instantiation then
> Node.Item will be a normal object of that type. Otherwise, it is
> implemented as a pointer but the code still treats it as an object.
> The target of the pointer is allocated on assignment of the object.
> The pointer cannot be copied to any other object. Assignments of the
> whole record will perform a deep-copy of the auto-allocated component.
> The target of the Node.Item pointer can be auto-deallocated when Node
> goes out of scope or is deallocated.
>
> Ok, I've probably missed something obvious and have been wasting my
> time, but at least I've got plenty of time to waste at the moment.
This looks interesting to me. There is a huge number of cases I am using
this schema, especially when Item is initialized once.
The major advantage is of course in having a plain String instead of
Unbounded_String. No conversions, no space/time penalties. I refrain
using Unbounded_String as much as possible.
Also there must be a possibility to specify the pool of Item. I
frequently place things like Node_Type into an arena pool, soI want the
string going there as well. Another case is marshaling such objects, so
that the body of Item would not be left behind.
--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
next prev parent reply other threads:[~2020-04-04 8:31 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-03 22:48 Proposal: Auto-allocation of Indefinite Objects Stephen Davies
2020-04-03 23:45 ` Stephen Leake
2020-04-04 10:54 ` Jeffrey R. Carter
2020-04-04 20:55 ` Stephen Davies
2020-04-04 8:31 ` Dmitry A. Kazakov [this message]
2020-07-27 7:47 ` Yannick Moy
2020-07-27 9:21 ` J-P. Rosen
2020-07-27 9:49 ` Dmitry A. Kazakov
2020-07-27 17:48 ` Brian Drummond
2020-07-27 20:02 ` Dmitry A. Kazakov
2020-07-28 14:28 ` Brian Drummond
2020-07-28 14:59 ` Dmitry A. Kazakov
2020-07-29 15:33 ` Brian Drummond
2020-07-29 16:20 ` Dmitry A. Kazakov
2020-07-30 13:37 ` Stephen Davies
2020-07-30 14:23 ` Dmitry A. Kazakov
2020-07-30 17:04 ` Brian Drummond
2020-07-30 18:28 ` Dmitry A. Kazakov
2020-08-10 0:39 ` Randy Brukardt
2020-08-10 8:57 ` Dmitry A. Kazakov
2020-08-20 0:10 ` Randy Brukardt
2020-08-20 17:49 ` Dmitry A. Kazakov
2020-08-20 20:19 ` Dennis Lee Bieber
2020-08-20 23:33 ` Randy Brukardt
2020-08-21 6:45 ` Dmitry A. Kazakov
2020-08-23 4:52 ` Randy Brukardt
2020-08-23 12:28 ` Dmitry A. Kazakov
2020-08-20 23:30 ` Randy Brukardt
2020-08-21 6:46 ` Dmitry A. Kazakov
2020-08-23 4:48 ` Randy Brukardt
2020-08-23 12:29 ` Dmitry A. Kazakov
2020-08-10 0:31 ` Randy Brukardt
2020-08-10 8:58 ` Dmitry A. Kazakov
2020-08-20 0:13 ` Randy Brukardt
2020-08-20 17:49 ` Dmitry A. Kazakov
2020-08-20 23:25 ` Randy Brukardt
2020-08-21 7:08 ` Dmitry A. Kazakov
2020-08-23 5:03 ` Randy Brukardt
2020-08-23 12:28 ` Dmitry A. Kazakov
2020-07-27 20:31 ` Jeffrey R. Carter
2020-07-31 9:25 ` Stephen Davies
2020-07-31 10:20 ` Dmitry A. Kazakov
2020-08-01 11:22 ` Stephen Davies
2020-08-01 12:58 ` Dmitry A. Kazakov
2020-08-01 20:35 ` Stephen Davies
2020-08-01 20:56 ` Dmitry A. Kazakov
2020-09-03 4:30 ` linda white
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