Re: [libstdc++ PATCH] libstdc++ debug mode

[Doug Gregor <dgregor at apple dot com>]

On Thursday, July 17, 2003, at 2:38AM, Gawain Bolton wrote:

> I think the debug mode patch you are proposing for libstdc++ is great. 
>  I
> would even say it is essential given the number of misuses of the C++
> standard library I have seen!  I especially like how iterators are
> automatically invalidated when performing operations which invalidate 
> them.

Glad I was able to get you interested :)

> I have a few questions though:
>     1. Why do you provide trivial destructors?  (For example: "~deque()
> { }").

Two reasons:
	1) Habit :)
	2) To generate the debug wrappers, I actually copied verbatim the 
synopsis sections of the standard and amended them according to DRs, so 
if the synopsis listed the destructor, I put in the {} instead of 
removing it. Interface accuracy is _very_ important to me.

>     2. Can a program (executable) be compiled with some parts using the
> debug version of libsdtc++ and others the nominal verson?

In the patch I supplied, no. I'm testing a different patch that allows 
mixing debug and non-debug (but gives up some of the checking behavior, 
unfortunately).

>         2.1 Along the same lines, but pushing things further, how 
> could one
> have debug mode turned on for a specific container type (eg. 
> std::list) or
> variable (e.g. just for variable "foo" of type std::map in bar()?

There isn't currently a way to turn on debug mode for a specific 
container template (e.g., std::list), but the debug wrappers are 
available in a separate namespace __gnu_cxx::debug. So if you want your 
"foo" to be a debugging std::map<...>, include <ext/debug/map> and 
change its type to __gnu_cxx::debug::map<...>. Depending on how your 
program references the name std::map, you might be able to pull some 
using declaration tricks to decide between the two :)

Note: the header location and namespace will be changing as requested 
by Benjamin, so don't rely on them just yet.

	Doug