How would I automate the creation of a default implementation of a class from an interface using conventions. In other words, if I have an interface:
public interface ISample
{
int SampleID {get; set;}
string SampleName {get; set;}
}
Is there a snippet, T4 template, or some other means of automatically generating the class below from the interface above? As you can see, I want to put the underscore before the name of the field and then make the field the same name as the property, but lower-case the first letter:
public class Sample
{
private int _sampleID;
public int SampleID
{
get { return _sampleID;}
set { _sampleID = value; }
}
private string _sampleName;
public string SampleName
{
get { return _sampleName;}
set { _sampleName = value; }
}
}
I am not sure if T4 would be the easiest solution here in terms of readability but you can also use another code generation tool at your disposal: the CodeDom provider .
The concept is very straightforward: code consists of building blocks that you put together.
When the time is ripe, these building blocks are then parsed into the language of choice . What you end up with is a string that contains the source code of your newly created program. Afterwards you can write this to a textfile to allow for further use.
As you have noticed: there is no compile-time result, everything is runtime. If you really want compiletime then you should use T4 instead.
The code:
using System;
using System.CodeDom;
using System.CodeDom.Compiler;
using System.IO;
using System.Reflection;
using System.Text;
namespace TTTTTest
{
internal class Program
{
private static void Main(string[] args)
{
new Program();
}
public Program()
{
// Create namespace
var myNs = new CodeNamespace("MyNamespace");
myNs.Imports.AddRange(new[]
{
new CodeNamespaceImport("System"),
new CodeNamespaceImport("System.Text")
});
// Create class
var myClass = new CodeTypeDeclaration("MyClass")
{
TypeAttributes = TypeAttributes.Public
};
// Add properties to class
var interfaceToUse = typeof (ISample);
foreach (var prop in interfaceToUse.GetProperties())
{
ImplementProperties(ref myClass, prop);
}
// Add class to namespace
myNs.Types.Add(myClass);
Console.WriteLine(GenerateCode(myNs));
Console.ReadKey();
}
private string GenerateCode(CodeNamespace ns)
{
var options = new CodeGeneratorOptions
{
BracingStyle = "C",
IndentString = " ",
BlankLinesBetweenMembers = false
};
var sb = new StringBuilder();
using (var writer = new StringWriter(sb))
{
CodeDomProvider.CreateProvider("C#").GenerateCodeFromNamespace(ns, writer, options);
}
return sb.ToString();
}
private void ImplementProperties(ref CodeTypeDeclaration myClass, PropertyInfo property)
{
// Add private backing field
var backingField = new CodeMemberField(property.PropertyType, GetBackingFieldName(property.Name))
{
Attributes = MemberAttributes.Private
};
// Add new property
var newProperty = new CodeMemberProperty
{
Attributes = MemberAttributes.Public | MemberAttributes.Final,
Type = new CodeTypeReference(property.PropertyType),
Name = property.Name
};
// Get reference to backing field
var backingRef = new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), backingField.Name);
// Add statement to getter
newProperty.GetStatements.Add(new CodeMethodReturnStatement(backingRef));
// Add statement to setter
newProperty.SetStatements.Add(
new CodeAssignStatement(
new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), backingField.Name),
new CodePropertySetValueReferenceExpression()));
// Add members to class
myClass.Members.Add(backingField);
myClass.Members.Add(newProperty);
}
private string GetBackingFieldName(string name)
{
return "_" + name.Substring(0, 1).ToLower() + name.Substring(1);
}
}
internal interface ISample
{
int SampleID { get; set; }
string SampleName { get; set; }
}
}
This produces:
Magnificent, isn't it?
Sidenote: a property is given Attributes = MemberAttributes.Public | MemberAttributes.Final
Attributes = MemberAttributes.Public | MemberAttributes.Final
because omitting the MemberAttributes.Final
would make it become virtual
.
And last but not least: the inspiration of this awesomeness. Metaprogramming in .NET by Kevin Hazzard and Jason Bock, Manning Publications.
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