Proper way to work around `Invalid memory operation`?

[Kapps via Digitalmars-d-learn]

On Sunday, 25 September 2016 at 16:07:12 UTC, Matthias Klumpp 
wrote:
> Hello!
>
> I have a class similar to this one:
> ```
> class Dummy
> {
>
> private:
>
>     string tmpDir;
>
> public:
>
>     this (string fname)
>     {
>         tmpDir = buildPath ("/tmp", fname.baseName);
>         std.file.mkdirRecurse (tmpDir);
>     }
>
>     ~this ()
>     {
>         close ();
>     }
>
>     void close ()
>     {
>         if (std.file.exists (tmpDir))
>                 std.file.rmdirRecurse (tmpDir);
>     }
> }
> ```
>
> When the GC calls the classes destructor, I get a
> `core.exception.InvalidMemoryOperationError@/<...>/ldc/runtime/druntime/src/core/exception.d(693): Invalid memory operation`
>
> Looks like rmdirRecurse tries to allocate with the GC, and the 
> GC doesn't like that.
> Is there any good way to get the temporary directory deletet 
> automatically when the object is freed?
> At time, I work around this bug by calling close() manually at 
> the appropriate time, but this feel like a rather poor solution.
>
> Cheers,
>     Matthias

As seen, you can't make GC allocations in dtors. And you should 
never rely on the GC calling your dtor to close things like file 
handles anyways. Consider making Dummy a struct and maybe using 
std.typecons(?).RefCounted with it.