clear() causes crash?

[Jonathan M Davis]

On Monday, April 29, 2013 23:04:29 =?UTF-8?B?Ikx1w61z?=.Marques 
<luismarques at gmail.com>@puremagic.com wrote:
> This crashes in the last line of main:
> 
> class A
> {
> void foo() {}
> }
> 
> void main()
> {
> A a = new A();
> a.foo();
> clear(a);
> assert(a !is null);
> a.foo(); // crashes
> }
> 
> As far as I understand from TDPL book, this should not crash, but
> it does (DMD64 v2.062, OS X). Am I misunderstanding clear()?
> 
> BTW, why not make clear also change 'a' to null?

I think that what TDPL says about clear may be outdated (I don't recall 
exactly what it said). But clear destroys the class object and zeroes out the 
vtbl, and it's invalid to do anything with the object after that. It's purely 
for cases where you want to destroy the object without waiting for the GC to 
do it (but it doesn't free any memory, so it's pretty much only of use for 
making sure that the destructor/finalizer gets run). It's very much on purpose 
that the app crashes when you use an object which you called clear on.

Also, clear has been renamed to destroy (leaving clear as an alias to 
destroy), so new code should be using destroy.

- Jonathan M Davis