vb.net - Find an item in an List(Of T) by values x, y, and z -

i have following setup:

class       property x string       property y int       property z string  end class  class collofa     inherits list(of a)  end class 

what item property in collection can say:

dim c new collofa c.item("this", 2, "that") 

i have tried implementing following in collofa:

class collofa     inherits list(of a)      default public overridable shadows readonly property item(byval x string, byval y integer, byval z string)                     ' want like:             ' foreach item in me see if matches these 3 things          end     end property end class 

i know predicates, struggling how set criteria of predicate (i.e. passing x, y, , z).

has implemented similar?

here's 2 ways came accomplish question. 1 way uses linq query syntax filter; second uses custom object hold predicate parameters , uses object perform filter.

using linq syntax in item property:

default public overridable shadows readonly property item(byval x string, byval y integer, byval z string) ienumerable(of a)             return (from thea in me                 (thea.x = x , thea.y = y , thea.z = z)                 select thea)      end end property 

the other way create predicateparameter class hold parameters , delegated method used execute filter. saw on msdn comment - here's link. here's class:

class predicateparams      public sub new(byval thea a)         criteria = thea     end sub      public property criteria      public function ismatch(byval thea a) boolean         return (thea.x = criteria.x , thea.y = criteria.y , thea.z = criteria.z)     end function  end class 

and here's property in collofa class uses it:

public overridable shadows readonly property itempred(byval x string, byval y integer, byval z string) ienumerable(of a)             dim preda new         preda.x = x         preda.y = y         preda.z = z          dim pred new predicateparams(preda)          return me.findall(addressof pred.ismatch)     end  end property 

lastly, here's console runner test this.

sub main()     dim mycoll new collofa()       index = 1 100         dim ana new a()         ana.x = (index mod 2).tostring()         ana.y = index mod 4         ana.z = (index mod 3).tostring()         mycoll.add(ana)     next      dim matched ienumerable(of a) = mycoll.item("1", 3, "2")     dim matched2 ienumerable(of a) = mycoll.itempred("1", 3, "2")      console.writeline(matched.count.tostring())  'output first search     console.writeline(matched2.count.tostring()) 'output second search (s/b same)     console.readline()  end sub 

hopefully helps. there may more elegant way this, didn't see one. (btw, work c#, vb.net little rusty.)