Thanks. Ali.
My previous post is not clear that I have to store class
reference(object pointer) in void*.
My actual code is try to use libuv in D.
// genarated from uv.h, only two fields is used: 'data', 'type'.
// the document of 'data': "Space for user-defined arbitrary
data. libuv does not use this field".
// uv_timer_t is the subclass of uv_handle_t in C. (uv_timer_t
has all the fields defined in uv_handle_t)
struct uv_handle_t {align(8):
union {
struct {void* data; void* _; uv_handle_type type;}
ubyte[96] _payload;
}
}
struct uv_timer_t {align(8):
union {
struct {void* data; void* _; uv_handle_type type;}
ubyte[160] _payload;
}
}
...
// try to resemble the libuv object defined in C.
struct UVHandle {
uv_handle_t _uvHandle;
// subclass uv_handle_t
alias _uvHandle this;
void close() { // uv_close(&this) }
bool isClosing() { // uv_is_closing(&this) }
...
}
// define Timer as 'final class', in order to force Timer
allocated in gc.
final class Timer {
UVHandle* uvHandle
// subclass UVHandle
alias uvHandle this;
...
this()
{
// malloc memory(nogc) for uv_timer_t.
uvHandle = malloc(uv_timer_t.sizeof)
// store the timer object reference in 'data',
// but 'alias uvHandle this' also overrides 'cast',
// this is the problem described as my previous post.
uvHandle.data = cast(void*) this;
}
~this() { free(uvHandle); }
void start(...) { // uv_timer_start(this.uvHandle, ...) }
void stop() { // uv_timer_stop(this.uvHandle) }
...
}
My current solution is using 'mixin template' instead of 'alias
this' as the way to subclass:
mixin template UVHandle() { ... }
public final class Timer {
mixin UVHandle;
...
}
