I have this condition
if(Model.Bids != null && Model.Bids.Items != null && Model.Bids.Items.Count > 0)
{
...
}
Problem
For c# this two options achieve sort of what you want but I wouldn't put this in my software quickly.
Also I doubt this gets more readable or better understandable. There is one other option but that requires you to refactor you Model class chain. If you implement a NullObject for the type in Bids
and the type in Item
you can do if(Model.Bids.Items.Count > 0)
because all types will not be null but have an implementation that handles the Empty state (much like String.Empty)
helpers
/* take a func, wrap in a try/catch, invoke compare */
bool tc(Func<bool> comp )
{
try
{
return comp.Invoke();
}
catch (Exception)
{
return false;
}
}
/* helper for f */
T1 f1<T,T1>(T root, Func<T, T1> p1) where T:class
{
T1 res = default(T1);
if (root != null)
{
res = p1.Invoke(root);
}
return res;
}
/* take a chain of funcs and a comp if the last
in the chain is still not null call comp (expand if needed) */
bool f<T,T1,T2,TL>( T root, Func<T,T1> p1, Func<T1,T2> p2, Func<T2,TL> plast,
Func<TL, bool> comp) where T:class where T1:class where T2:class
{
var allbutLast = f1(f1(root, p1), p2);
return allbutLast != null && comp(plast.Invoke(allbutLast));
}
Usage
var m = new Model();
if (f(m, p => p.Bids, p => p.Items, p => p.Count, p => p > 0))
{
Debug.WriteLine("f");
}
if (tc(() => m.Bids.Items.Count > 0))
{
Debug.WriteLine("tc ");
}
if (m.Bids != null && m.Bids.Items != null && m.Bids.Items.Count > 0)
{
Debug.WriteLine("plain");
}