public static Func <CancellationToken, TParam, Task <TResult> > AsMemoized <TParam, TResult>(this Func <CancellationToken, TParam, Task <TResult> > func)
{
var values = new SynchronizedDictionary <TParam, Func <CancellationToken, Task <TResult> > >();
// It's safe to use default(TParam) as this won't get called anyway if TParam is a vlue type.
var nullValue = Funcs.CreateAsyncMemoized(ct => func(ct, default(TParam)));
return((ct, param) =>
{
if (param == null)
{
return nullValue(ct);
}
else
{
var memoizedFunc = values.FindOrCreate(param, () => Funcs.CreateMemoized(c => func(c, param)));
return memoizedFunc(ct);
}
});
}
