Re: Smart pointers was RE: [GD-General] Compile times

[Jesse J. <jes...@mi...>]

At 11:51 AM -0600 12/16/02, brian hook wrote:
>  > >- non-deterministic destruction (a problem with general GC as well)
>>
>>  How so? With a real GC objects aren't deleted until the collector
>>  gets around to freeing them, but with all the ref-counted smart
>>  pointer classes I've seen they are deleted when the last reference is
>>  released.
>
>Non-deterministic was a poor choice of phrase.  More
>like "unpredictable" because, by definition, if you're using smart
>pointers you've opted to stop thinking about de-allocation of memory. 
>So you're never quite sure when the "last reference" is released, since
>that can change as the code evolves.

Yep, but I haven't found this to be an issue.

>  > >- cascading destruction if you deref a root node
>>
>>  Why is this a problem?
>
>Because along with "unpredictable de-allocation", it can lead to
>cascades that may cause a hiccup in your system.  If you have
>heavyweight destructors, having a bunch of them called instantly
>because you did this:
>
>foo->pBar = NULL;
>
>is both non-obvious (if you haven't been able to tell, I also abhor
>code that looks straightforward but may actually do a bunch of non-
>obvious stuff) and annoying.

I will grant you non-obvious (especially if you haven't used a 
garbage collected language much), but it seems to me any hiccups will 
come about at pretty much the same place in the game whether or not 
you use reference counting.

>  > Well, what are the options? In my experience automating reference
>>  counting with smart pointers is a hell of a lot better than doing it
>>  manually.
>
>My experience has been the opposite.  My anecdote can kick your
>anecdotes ass! =)

So, you've actually used manual ref counting Brian? InDesign used ref 
counting like crazy and the newer code that used smart pointers was 
noticeably cleaner than the old code.

>  > Doing all the memory management manually with naked calls
>>  to new and delete is feasible with discipline and some programming
>>  conventions, but there are usually a few instances where this becomes
>>  difficult.
>
>Where is it difficult to rely on convention and discipline?

The biggest problem is that it doesn't scale well. It's yet another 
thing for new coders to learn and another thing for busy people to 
remember to do. All other things being equal it's much better to 
design the system so that you don't have to rely on a convention.

   -- Jesse