manual memory management

[Paulo Pinto]

On Wednesday, 9 January 2013 at 02:49:34 UTC, Rob T wrote:
> On Tuesday, 8 January 2013 at 23:30:34 UTC, David Nadlinger 
> wrote:
>> On Tuesday, 8 January 2013 at 23:12:43 UTC, Rob T wrote:
>>> The only major thing that concerns me is the lack of proper 
>>> shared library support. I hope this omission is resolved soon.
>>
>> What do you need it for? Runtime loading of D shared objects? 
>> Or just linking to them (i.e. binding by ld/dyld at load 
>> time)? I'm trying to collect data on real-world use cases 
>> resp. expectations right now.
>>
>> David
>
> I *really* need runtime loading of plug-in code for a server 
> application. This allows the server code to remain untouched 
> while allowing extensions to be added on by a 3rd party.
>
> Runtime linked shared libs are also nice to have for the simple 
> reason that shared libraries can be updated (to a point) 
> without having to rebuild and relink all applications that make 
> use of the libraries. There are pros and cons to static vs 
> dynamic linking, but definitely both are useful to have.
>
> I'm very surprised that not too many people have been screaming 
> for dynamic linking and runtime loading. It's very hard for me 
> to imagine not having the feature because it's so darn useful 
> and an essential feature if your strategy is to allow 3rd 
> parties to extend an application without hacking at the source 
> code.
>
> If there's another better way, I'd sure like to know about it!
>
> --rt

You can write plugins without dynamic loading, they just are a 
bit more cumbersome to write.

Like I used to do back in the late 90's, by making use of UNIX's 
IPC.

The IPC to use (shared memory, pipes, mailbox, sockets) depends 
on what is required from the plugin. With shared memory being the 
closest to what dynamic loading achieves.

Of course this raises another set of issues like:

- Take care what happens when a plugin dies
- Too many loaded plugins can stress the scheduler
- You might have synchronization issues when using shared memory
- It is a bit more painful to code for

This is the school of thought of the Plan9/Go guys and most 
operating system micro-kernel architectures.

--
Paulo