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added a CopyConstructor attribute to CopyExtensions

This commit is contained in:
Ellpeck 2020-10-25 20:11:15 +01:00
parent f68e55ebfd
commit 500025090f
2 changed files with 27 additions and 9 deletions

View file

@ -1,4 +1,5 @@
using System;
using System.Linq;
using System.Reflection;
namespace MLEM.Data {
@ -11,7 +12,7 @@ namespace MLEM.Data {
/// <summary>
/// Creates a shallow copy of the object and returns it.
/// Note that, for this to work correctly, <typeparamref name="T"/> needs to contain a parameterless constructor.
/// Note that, for this to work correctly, <typeparamref name="T"/> needs to contain a parameterless constructor or a constructor with the <see cref="CopyConstructorAttribute"/>.
/// </summary>
/// <param name="obj">The object to create a shallow copy of</param>
/// <param name="flags">The binding flags for field searching</param>
@ -26,7 +27,7 @@ namespace MLEM.Data {
/// <summary>
/// Creates a deep copy of the object and returns it.
/// Note that, for this to work correctly, <typeparamref name="T"/> needs to contain a parameterless constructor.
/// Note that, for this to work correctly, <typeparamref name="T"/> needs to contain a parameterless constructor or a constructor with the <see cref="CopyConstructorAttribute"/>.
/// </summary>
/// <param name="obj">The object to create a deep copy of</param>
/// <param name="flags">The binding flags for field searching</param>
@ -56,7 +57,7 @@ namespace MLEM.Data {
/// <summary>
/// Copies the given object <paramref name="obj"/> into the given object <paramref name="otherObj"/> in a deep manner.
/// Note that, for this to work correctly, each type that should be constructed below the topmost level needs to contanin a parameterless constructor.
/// Note that, for this to work correctly, each type that should be constructed below the topmost level needs to contanin a parameterless constructor or a constructor with the <see cref="CopyConstructorAttribute"/>.
/// </summary>
/// <param name="obj">The object to create a deep copy of</param>
/// <param name="otherObj">The object to copy into</param>
@ -84,11 +85,23 @@ namespace MLEM.Data {
}
private static object Construct(Type t, BindingFlags flags) {
var constructor = t.GetConstructor(flags, null, Type.EmptyTypes, null);
// find a contructor with the correct attribute
var constructor = t.GetConstructors().FirstOrDefault(c => c.GetCustomAttribute<CopyConstructorAttribute>() != null);
// fall back to a parameterless constructor
if (constructor == null)
throw new NullReferenceException($"Type {t} does not have a parameterless constructor with the required visibility");
return constructor.Invoke(null);
constructor = t.GetConstructor(flags, null, Type.EmptyTypes, null);
if (constructor == null)
throw new NullReferenceException($"Type {t} does not have a parameterless constructor with the required visibility or a constructor with the CopyConstructorAttribute");
return constructor.Invoke(new object[constructor.GetParameters().Length]);
}
}
/// <summary>
/// An attribute that, when added to a constructor, will make that constructor the one used by <see cref="CopyExtensions.Copy{T}"/>, <see cref="CopyExtensions.DeepCopy{T}"/> and <see cref="CopyExtensions.DeepCopyInto{T}"/>.
/// </summary>
[AttributeUsage(AttributeTargets.Constructor)]
public class CopyConstructorAttribute : Attribute {
}
}

View file

@ -89,11 +89,11 @@ namespace Sandbox {
panel.SetData("TestKey", new Vector2(10, 2));
//Console.WriteLine(panel.GetData<Vector2>("TestKey"));
var obj = new Test {
var obj = new Test(Vector2.One, "test") {
Vec = new Vector2(10, 20),
Point = new Point(20, 30),
Dir = Direction2.Left,
OtherTest = new Test {
OtherTest = new Test(Vector2.One, "other") {
Vec = new Vector2(70, 30),
Dir = Direction2.Right
}
@ -110,7 +110,7 @@ namespace Sandbox {
var copy = obj.DeepCopy();
Console.WriteLine(copy);
var intoCopy = new Test {OtherTest = new Test()};
var intoCopy = new Test(Vector2.One, "test") {OtherTest = new Test(Vector2.One, "other")};
obj.DeepCopyInto(intoCopy);
Console.WriteLine(intoCopy);
@ -234,6 +234,11 @@ namespace Sandbox {
public Direction2 Dir { get; set; }
public Test OtherTest;
[CopyConstructor]
public Test(Vector2 test, string test2) {
Console.WriteLine("Constructed with " + test + ", " + test2);
}
public override string ToString() {
return $"{this.GetHashCode()}: {nameof(this.Vec)}: {this.Vec}, {nameof(this.Point)}: {this.Point}, {nameof(this.OtherTest)}: {this.OtherTest}, {nameof(this.Dir)}: {this.Dir}";
}