public ViewModel LookupOrCreate(object key, Func <ViewModel> create)
{
if (key == null)
{
throw new ArgumentNullException("key");
}
if (create == null)
{
throw new ArgumentNullException("create");
}
_perfCounter.IncrementViewModelFetch();
var result = _cache.ContainsKey(key) ? _cache[key] : null;
if (result != null)
{
return(result);
}
_perfCounter.IncrementViewModelCreate();
result = create();
_cache[key] = result;
return(result);
}
