Represents a reference to a default value.
See Also: CodeDefaultValueExpression Members
Syntax
[System.Runtime.InteropServices.ComVisible(true)]
public class CodeDefaultValueExpression : CodeExpression
Remarks
A System.CodeDom.CodeDefaultValueExpression can be used to represent a reference to a default value.
The CodeDefaultValueExpression.Type property specifies the reference to the value type. The System.CodeDom.CodeDefaultValueExpression class is used in the generation of generics-based code. For more information on generics, see Generics in the Base Class Library. The following code steps are provided in this section to further describe the use of the System.CodeDom.CodeDefaultValueExpression class to add a new default value to a code graph.
The code in part 1 is part of a larger example provided for the System.CodeDom.CodeTypeParameter class. This code, when run through the C# code generator, results in the C# code that appears in part 2. When this code is called in the statement in part 3, the result is the output shown in part 4.
Example
// Part 1: Code to create a generic Print method.
CodeMemberMethod printMethod = new CodeMemberMethod();
CodeTypeParameter sType = new CodeTypeParameter("S");
sType.HasConstructorConstraint = true;
CodeTypeParameter tType = new CodeTypeParameter("T");
sType.HasConstructorConstraint = true;
printMethod.Name = "Print";
printMethod.TypeParameters.Add(sType);
printMethod.TypeParameters.Add(tType);
printMethod.Statements.Add(ConsoleWriteLineStatement(
new CodeDefaultValueExpression(new CodeTypeReference("T"))));
printMethod.Statements.Add(ConsoleWriteLineStatement(
new CodeDefaultValueExpression(new CodeTypeReference("S"))));
Example
// Part 2: Code generated by code in part 1.
public virtual void Print<S, T>()
where S : new()
{
Console.WriteLine(default(T));
Console.WriteLine(default(S));
}
Example
// Part 3: Call to the generated method. dict.Print<System.Decimal, int>();
Example
// Part 4: Output of the generated method. 0 0
Requirements
Assembly: System (in System.dll)
Assembly Versions: 2.0.0.0, 4.0.0.0
Since: .NET 2.0