/// <summary>
/// Constructs a new instance of <see cref="LazyInitObject{T}"/>.
/// </summary>
///
/// <param name="initFunc">A delegate that must be called during initialization to obtain the
/// object's value.</param>
/// <param name="initLock">An object that will be used as a lock to ensure thread safe
/// initialization. If this is null, a lock object is created internally and used.</param>
/// <param name="recursionHandling">Specifies how accesses to the object within the
/// initialization function are handled.</param>
public LazyInitObject(
Func <T> initFunc,
object?initLock = null,
LazyInitRecursionHandling recursionHandling = LazyInitRecursionHandling.THROW
)
{
if (initFunc == null)
{
throw new ArgumentNullException(nameof(initFunc));
}
if (recursionHandling > LazyInitRecursionHandling.RECURSIVE_CALL)
{
throw new ArgumentOutOfRangeException(nameof(recursionHandling));
}
if (initLock == null)
{
initLock = new object();
}
m_value = default(T);
m_initFunc = initFunc;
m_initLock = initLock;
m_recursionHandler = recursionHandling;
m_state = LazyInitObjectState.UNINITIALIZED;
}
private T _internalGetValue()
{
if (m_initLock == null)
{
throw new InvalidOperationException("Cannot access the value of a default-initialized LazyInitObject.");
}
lock (m_initLock) {
LazyInitObjectState state = m_state;
if (state == LazyInitObjectState.COMPLETE)
{
return(m_value !);
}
if (state == LazyInitObjectState.FAILED)
{
throw new InvalidOperationException("Cannot access lazy object after initialization failure.");
}
if (state == LazyInitObjectState.IN_INITIALIZER)
{
if (m_recursionHandler == LazyInitRecursionHandling.THROW)
{
throw new InvalidOperationException("Cannot access lazy object in initializer.");
}
if (m_recursionHandler == LazyInitRecursionHandling.RETURN_DEFAULT)
{
return(default(T) !);
}
}
m_state = LazyInitObjectState.IN_INITIALIZER;
T value;
try {
value = m_initFunc();
}
catch {
m_state = LazyInitObjectState.FAILED;
m_initFunc = null !; // This will never be called again
throw;
}
m_value = value;
m_state = LazyInitObjectState.COMPLETE;
m_initFunc = null !; // This will never be called again
return(value);
}
}