如何创建泛型类型的类新实例实例、类型
问题：
如何创建，设置，返回和实例类型为T的对象？ 我将如何访问子类型（标签：数据库）？在静态函数我想创建一个通用的GetAsClass功能，它会返回一个子类的初始化实例。我无法弄清楚如何创造我想要返回，返回子类类型的类的新实例。
I'm trying to create a generic "GetAsClass" function which would return an initialized instance of the subclass. I can't figure out how to create a new instance of the class I want to return and return the subclass type.
说我有两个类：
标签 用户我要创建这将让任何类型它的基类的单一功能。在另一方面，我想，使其静态以及（但我没有获得这个，我不知道如何让子类类型。
I want to create a single function in the base class which will get whatever type it is. On another note, I'd like to make it static as well (but then I don't have access to "this" and I'm not sure how to get the subclass type.
private async Task<T> GetAsClass<T>(string objectId) {
Type classType = this.GetType();
string className = classType.Name;
// This needs to be of type "T" (Tag myTag = new Tag();) How would I accomplish something like this?
object toReturnObject = new object();
ParseObject myParseObject = ParseObject.GetAsParseObject(objectId);
foreach (PropertyInfo field in classType.GetRuntimeProperties()) {
if (field.CanRead) {
string propertyName = StringHelper.ToLowerCamelCase(field.Name);
if (field.PropertyType == typeof(string)) {
string propertyValue = myParseObject.Get<string>(propertyName);
field.SetValue(toReturnObject , propertyValue);
}
if (field.PropertyType == typeof(int)) {
int propertyValue = myParseObject.Get<int>(propertyName);
field.SetValue(toReturnObject, propertyValue);
}
}
}
return toReturnObject;
}
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推荐答案
您可能会发现此页面上的泛型类型约束的是有帮助的。 基本上，你会改变你的类的签名/方法是：
You may find this page on generic type constraints to be helpful. Basically, you would change the signature of your class/method to be:
private async Task<T> GetAsClass<T>(string objectId)
where T: new()
{
...
}
和它将接受类型的T，只有当它提供了一个默认的构造函数不带参数。一旦条件得到保证，那么你的类可以调用新T（）
And it will accept types of T only if it provides a default constructor with no arguments. Once that condition is guaranteed, then your class can invoke new T()
