C# - 如何在不使用反射的情况下获取/设置对象的属性值
本文关键字:设置 获取 对象 属性 情况下 反射的 | 更新日期: 2023-09-27 18:31:16
我需要能够存储对对象属性的引用,以便以后读取/写入它,理想情况下不使用反射。 我也对一种有效的设计模式持开放态度,但性能至关重要,因为我的应用程序将进行数百万次调用以在各种"父"类上"运行"。 下面的代码模板应该解释我正在尝试做什么。
例如,我想保持它,即我"需要"的变量是 Child 类的对象属性,而不是存储在某个列表中的数据结构。
最后,我想我正在寻找超越重置对象值或检查不为空的东西。 例如,在调用_run后,Parent 可能会将属性的值用于其他内容。
谢谢。
class requiredAttribute : Attribute
{
}
abstract class Parent
{
abstract protected void _run();
public Parent() {
// This can do whatever set-up is necessary in order to make the below run() call
// not need reflection.
/* What code goes here? */
}
public void run() {
// This code should reset all 'required' properties to null.
/* What goes here? */
_run();
// This code needs to ensure any required property is now not null.
// If it finds a null one, it should throw.
/* What goes here? */
}
}
class Child : Parent
{
[required]
protected object value1;
[required]
protected object value2;
// not required..
protected object value3;
protected void _run() {
// This must set all 'required' properties' values, otherwise the Parent should throw.
value1 = "some value";
value2 = "some other value";
}
}
与其使用
an 属性,不如使用接口。
创建一个接口IValidatable
并将其放置在父接口上。
为父级提供它的抽象实现。并在孩子身上实施它。
abstract class Parent : IValidatable
{
public abstract bool IsValid();
abstract protected void _run();
public Parent()
{
}
public void run()
{
_run();
if (!IsValid())
//throw
}
}
class Child : Parent
{
protected object value1;
protected object value2;
// not required..
protected object value3;
protected override void _run()
{
// This must set all 'required' properties' values, otherwise the Parent should throw.
value1 = "some value";
value2 = "some other value";
}
public override bool IsValid()
{
return value1 != null && value2 != null;
}
}
public interface IValidatable
{
bool IsValid();
}
我找到了一个运行良好的高性能反射库:FastMember。
using FastMember;
class RequiredAttribute : Attribute
{
}
abstract class Parent
{
abstract protected void _run();
private List<string> required_prop_names = new List<string>();
private ObjectAccessor accessor;
public Parent()
{
// create list of properties that are 'required'
required_prop_names = this.GetType().GetFields()
.Where(prop => Attribute.IsDefined(prop, typeof(RequiredAttribute)))
.Select(prop => prop.Name)
.ToList<string>();
// create FastMember accessor
accessor = ObjectAccessor.Create(this);
}
public void run()
{
// set all to null
required_prop_names.ForEach(x => accessor[x] = null);
// call child
_run();
// validate
foreach (string prop_name in required_prop_names){
Console.WriteLine("Value of {0} is {1}", prop_name, accessor[prop_name]);
if (accessor[prop_name] == null){
Console.WriteLine("Null value found on {}!", prop_name);
}
}
}
}
class Child : Parent
{
[Required]
public object value1 = "something";
[Required]
public object value2 = "something";
// not required..
public object value3;
override protected void _run()
{
// This must set all 'required' properties' values, otherwise the Parent should throw.
value1 = "something else";
//value2 = "something else";
}
}
另一种解决方案使用 Wrapper 对象——这样我们就可以存储对这些对象的引用,并在以后获取/设置它们。 为方便起见,可以使用反射由基对象自动创建包装器实例。 唯一的问题是在 _run() 中,您必须执行 value1.value = "某个值"而不是 value1 = "某个值"。 公平贸易,国际海事组织。
此解决方案只需要在实例化时进行反射,并且仍然保持类型(为了智能感知的好处)
代码看起来像这样......还没有测试过它,但这是一般的想法。
class Wrapper {
public object value;
}
class Wrapper<T> : Wrapper {
new public T value;
}
class requiredAttribute : Attribute
{
}
abstract class Parent
{
abstract protected void _run();
private List<Wrapper> wrappers = new List<Wrapper>();
public Parent() {
// Use reflection to find all fields that have a 'required' attribute.
// For each one, instantiate an instance of Wrapper<T>
// Store the reference to each object so that in run() we can reset and validate.
/* code that does above statement goes here. */
}
public void run() {
foreach (Wrapper wrapper in wrappers){
wrapper.value = null;
}
_run();
foreach (Wrapper wrapper in wrappers){
if (wrapper.value == null) throw new Exception("null value found");
}
}
}
class Child : Parent
{
[required]
protected Wrapper<string> value1;
[required]
protected Wrapper<int> value2;
// not required..
protected object value3;
protected void _run() {
// This must set all 'required' properties' values, otherwise the Parent should throw.
value1.value = "some value";
value2.value = 123;
}
}