query to detect ISP violations

Question

I am trying to create a special query with NDepend, but cannot figure it out.

Here's what I'd like to query in a more procedural pseudocode:

var list
foreach type t
    foreach i = t.attribute that is an interface
        var nm = i.numberOfMethods
        var mu = numberOfMethods that t actually uses
        if mu / nm < 1
        list.Add(t)
    end foreach
end foreach
return list

It's supposed to list types that don't comply with the Interface Segregation Principle.

Thanks!

Answer 1

So the query you ask can be written this way:

from t in JustMyCode.Types where !t.IsAbstract

from i in t.TypesUsed where i.IsInterface

// Here collect methods of i that are not used
let methodsOfInterfaceUnused = i.Methods.Where(m => !m.IsUsedBy(t))
where methodsOfInterfaceUnused.Count() > 0
select new { t, methodsOfInterfaceUnused }

This query has the peculiarity to match several time a same type, one for each time methodsOfInterfaceUnused is not empty. The result is then nicely presented and understandable: