[英]Casting to generic type fails in c#
I'd wish to save some coding by being able to create a dynamic GetControl method. 我希望通过创建动态GetControl方法来节省一些编码。 My ideas is something like this
我的想法是这样的
private T GetControl<T>(ASPxGridView control, string element)
{
var returnedElement = (T)control.FindEditFormTemplateControl(element);
return returnedElement;
}
Which I call with 我打电话给
var myElement = GetControl<ASPxTextBox>(myGridView, "UserId");
But, this fails miserably: 但是,这不幸地失败了:
Cannot convert type 'System.Web.UI.Control' to 'T'
无法将类型“ System.Web.UI.Control”转换为“ T”
Any advices? 有什么建议吗?
Try adding a generic constraint: 尝试添加通用约束:
private T GetControl<T>(ASPxGridView control, string element) where T : Control
{
var returnedElement = (T)control.FindEditFormTemplateControl(element);
return returnedElement;
}
You can circumvent type safety by casting via object
: 您可以通过
object
进行投射来规避类型安全:
var returnedElement = (T)(object)control.FindEditFormTemplateControl(element);
Furthermore, I would constrain your generic type to Web.UI.Control
, if only for the purpose of self-documentation: 此外,如果仅出于自我说明的目的,我会将您的泛型类型限制为
Web.UI.Control
:
private T GetControl<T>(ASPxGridView control, string element)
where T: System.Web.UI.Control
{
return (T)control.FindEditFormTemplateControl(element);
}
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