On Sunday, 31 January 2016 at 18:02:19 UTC, Matt Elkins wrote:
Here is the one I am using right now:
Actually, here is the whole module in case you are interested in
the unittests/usage:
[code]
import std.algorithm;
import std.traits;
struct ResourceHandle(T, alias Deleter, T Default = T.init)
{
// Constructors/Destructor
this(in T handle) {m_handle = handle;}
@disable this(this);
~this() {Deleter(m_handle);}
// Operators
@disable void opAssign(ref ResourceHandle lvalue);
ref ResourceHandle opAssign(ResourceHandle rvalue)
{swap(m_handle, rvalue.m_handle); return this;}
// Methods
@property T handle() const {return m_handle;}
@property T handle(T handle) {Deleter(m_handle); m_handle =
handle; return m_handle;}
T release() {T result = m_handle; m_handle = Default; return
result;}
private:
T m_handle = Default;
}
@nogc @safe nothrow unittest
{
static uint destroyedCount;
static uint lastDestroyed;
alias RH = ResourceHandle!(uint, (uint resource){if (resource
!= uint.init) {lastDestroyed = resource; ++destroyedCount;}});
// Test basic resource cleanup
assert(destroyedCount == 0);
assert(lastDestroyed != 7);
{auto handle0 = RH(7);}
assert(destroyedCount == 1);
assert(lastDestroyed == 7);
// Test releasing
{
auto handle0 = RH(8);
assert(handle0.handle == 8);
assert(handle0.release() == 8);
assert(handle0.handle == uint.init);
assert(destroyedCount == 1);
assert(lastDestroyed == 7);
}
assert(destroyedCount == 1);
assert(lastDestroyed == 7);
{
// Test that copying and lvalue assignment are disabled
auto handle0 = RH(5);
static assert (!__traits(compiles, {auto handle1 =
handle0;}));
static assert (!__traits(compiles, {RH handle1; handle1 =
handle0;}));
// Test that rvalue assignment works
auto makeRH(uint value) {return RH(value);}
handle0 = makeRH(3);
assert(destroyedCount == 2);
assert(lastDestroyed == 5);
}
assert(destroyedCount == 3);
assert(lastDestroyed == 3);
// Test setting in static array
{
RH[3] handles;
handles[0] = RH(9);
assert(destroyedCount == 3);
assert(lastDestroyed == 3);
}
assert(destroyedCount == 4);
assert(lastDestroyed == 9);
// Test setting to resource directly
{
auto handle0 = RH(11);
assert(destroyedCount == 4);
assert(lastDestroyed == 9);
assert(handle0.handle == 11);
handle0.handle = 12;
assert(destroyedCount == 5);
assert(lastDestroyed == 11);
assert(handle0.handle == 12);
}
assert(destroyedCount == 6);
assert(lastDestroyed == 12);
}
[/code]
