[英]Get default value of class member
Let's assume I have a class ClassWithMember 我们假设我有一个ClassWithMember类
class ClassWithMember
{
int myIntMember = 10;
}
How do I get the default value 10 of the myIntMember member by System.Type? 如何通过System.Type获取myIntMember成员的默认值10?
I'm currently struggling around with reflections by all I retreive is the default value of int (0) not the classes default member (10).. 我目前正在努力解决所有我的反思是int(0)的默认值而不是类默认成员(10)..
You can try something like this: 你可以尝试这样的事情:
var field = typeof(ClassWithMember).GetField("myIntMember",
BindingFlags.Instance | BindingFlags.NonPublic);
var value = (int)field.GetValue(new ClassWithMember());
The trick here is to instantiate an instance. 这里的技巧是实例化一个实例。
尝试创建一个实例,用反射来检索值。
If you're in control of the code for ClassWithMember, you could take a completely different approach to this by using the [DefaultValue]
attribute from System.ComponentModel
. 如果您控制ClassWithMember的代码,则可以使用System.ComponentModel
的[DefaultValue]
属性采用完全不同的方法。 Basically, what you'd do is write something like this: 基本上,你要做的是写这样的东西:
class ClassWithMember
{
public ClassWithMember()
{
SetDefaultValues();
}
[DefaultValue(5)]
public MyIntMember { get; set; }
}
And then have a function like this somewhere, perhaps in a base class: 然后在某个地方有一个这样的函数,也许在基类中:
public void SetDefaultValues()
{
foreach (PropertyDescriptor prop in TypeDescriptor.GetProperties(this))
{
DefaultValueAttribute a = prop.Attributes[typeof(DefaultValueAttribute)] as DefaultValueAttribute;
if (a == null)
continue;
prop.SetValue(this, a.Value);
}
}
So now, you have a situation where you can easily retrieve the default values using Reflection. 现在,您可以使用Reflection轻松检索默认值。
Keep in mind that this is going to be quite a lot slower due to the Reflection requirement, so if this code gets instantiated a lot, you'll probably want to find a different approach. 请记住,由于Reflection要求,这将变得非常慢,所以如果这个代码被大量实例化,你可能想要找到一个不同的方法。 Also, it won't work with non-value types, due to a limitation with the .NET Framework's attribute support. 此外,由于.NET Framework的属性支持的限制,它不适用于非值类型。
You can still use Activator.CreateInstance to create a MonoBehaviour/ScriptableObject and check its values, if it's simply for the sake of checking the default Values. 您仍然可以使用Activator.CreateInstance创建MonoBehaviour / ScriptableObject并检查其值,如果它只是为了检查默认值。 Make sure to use DestroyImmediate afterwards ;-) 确保之后使用DestroyImmediate ;-)
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