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I am going brain dead on this; I have several List' defined, based on specific classes (c1, c2, c3...). I have a method that will process information on these lists. What I want to do is pass in the specific list, but have the method accept the generic list, and then via typeof determine what specific work to do. I know its possible, but I cant seem to get the syntax right on the method side. so, for example:
List<c1> c1var; List<c2> c2var; List<c3> c3var; some_method(c1var); some_method(c2var); some_method(c3var); class some_thing some_method(List<> somevar) if typeof(somevar).name = x then esle if typeof(somevar).name = y then.... How do I set up the parameter list for the method?
thanks in advance R. Sanders
871
The ListBox is using the ToString() method of the Generic List which returns a description of it (which is what you see) NOT it's contents. To get that you will have to write your own class which inherits from List<> and in that class write your own ToString() method which returns a string in the format you like.
T is called type parameter, which can be used as a type of fields, properties, method parameters, return types, and delegates in the DataStore class. For example, Data is generic property because we have used a type parameter T as its type instead of the specific data type.
You can't declare a list of generic types without knowing the generic type at compile time. You can declare a List<Field<int>> or a List<Field<double>> , but there is no other common base type for Field<int> and Field<double> than object .
The where clause in a generic definition specifies constraints on the types that are used as arguments for type parameters in a generic type, method, delegate, or local function. Constraints can specify interfaces, base classes, or require a generic type to be a reference, value, or unmanaged type.
You need to declare some_method to be generic, as well.
void SomeMethod<T>(List<T> someList) { if (typeof(T) == typeof(c1)) { // etc } } Careful with the use of typeof(typ1) == typeof(typ2). That will test to see if the types are equivalent disregarding the type hierarchy.
For example:
typeof(MemoryStream) == typeof(Stream); // evaluates to false new MemoryStream() is Stream; //evalutes to true A better way to check to see if an object is of a type is to use the 'is' keyword. An example is below:
public static void RunSnippet() { List<c1> m1 = new List<c1>(); List<c2> m2 = new List<c2>(); List<c3> m3 = new List<c3>(); MyMeth(m1); MyMeth(m2); MyMeth(m3); } public static void MyMeth<T>(List<T> a) { if (a is List<c1>) { WL("c1"); } else if (a is List<c2>) { WL("c2"); } else if (a is List<c3>) { WL("c3"); } } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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