Proposal : allocations made easier with non nullable types.

[Andrei Alexandrescu]

dsimcha wrote:
> == Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s article
>> Chad J wrote:
>>> Besides safety concerns, what does forbidding manual deletion enable GC
>>> implementations to do?
>> Foregoing delete affords the GC more implementation options.
>> Andrei
> 
> Let's assume this is true and that these options are things that are useful to a
> language like D.  Worst case scenario, a GC implementation could just ignore calls
> to GC.free().  GC.free() could just be implementation defined as either frees
> memory or does nothing.

Sure, but making GC.free() offer no guarantee makes it rather useless. 
It's actually worse than useless because you see a call to GC and you 
don't know whether or not that could mess up your heap, and you also 
don't know whether or not that can get you any memory.

> As far as safety, D is a systems programming language.  If you really want to
> manually delete a piece of GC-allocated memory, you should be able to.  It's good
> for a systems language to make it harder to screw up _by accident_ (I'm all for
> getting rid of the delete keyword to make deleting GC-allocated memory less
> obvious), but if you insist on doing something, the language should assume you
> have a good reason.  Deleting GC allocated memory is an advanced technique that
> you do at your own risk, just like using C's malloc/free, using pointers, turning
> off bounds checking, casting, using inline assembly, not initializing variables at
> declaration, and all the other dangerous but sometimes useful stuff that "safe"
> languages won't let you do.  Disabling this wouldn't absolutely prevent corruption
> of the GC heap since D still has pointers, which in principle could be made to
> point anywhere, and since one could still do something stupid like store the only
> pointer to an object in a region not scanned by the GC via casting or something.
> The bottom line is that I fail to see how deleting GC-allocated memory is any
> different than other dangerous but useful things that can be done in D, and unless
> we want to make D a completely safe language at the expense of the flexibility
> that its unsafeness offers, I don't understand why you're so opposed to it.

Because you have malloc. If you didn't, I'd be all with you. Just use 
malloc and leave the GC heap alone. It's the perfect setup.


Andrei