如何检查是否存在COM属性或方法，而不会产生异常？ [英] How to check if a COM property or method exists without generating an exception?
问题描述
我工作的一些遗留code，它创建一个包含属性和/或方法名字符串列表，然后尝试这些属性或方法适用于COM对象。该属性或方法的COM对象不能保证存在，它可以是一个属性或方法，我不知道是哪个。
I'm working on some legacy code that creates a list of strings containing property and/or method names and then attempts to apply those properties or methods to a COM object. The property or method for the COM object is not guaranteed to exist and it could be either a property or a method I don't know which.
目前，如果一个属性或方法不存在，它抓住了一个COM异常。这会导致性能不佳。我试图找到一种方法来检查，如果一个属性或方法存在于一个COM对象，而不会产生异常，这样我可以尝试使用它之前检查它的存在。
At the moment if a property or method doesn't exist it's caught as a COM exception. This results in poor performance. I am trying to find a way to check if a property or method exists in a COM object without generating an exception so that I can check for its existence before attempting to apply it.
使用的GetType返回类型为System.com_object。在System.com_object使用的getProperty因为这不能解决问题是确切的运行时类型不是它的衍生型。相反，我要InvokeMember如果成员不存在它创建一个例外。有没有人有这样做的更好的办法？
Using GetType returns type System.com_object. Using GetProperty on System.com_object doesn't work as this is the exact runtime type not the type it's derived from. Instead I have to InvokeMember which creates an exception if the member doesn't exist. Does anyone have a better way of doing this?
我在 .NET 3.5 目前的工作。迁移到.NET 4是不是在present一个选项，但我还是有兴趣的解决方案在.NET 4中，如果新的语言功能提供了解决问题的更好的方法。
I'm working in .NET 3.5 at the moment. Migration to .NET 4 is not an option at present but I'd still be interested in solutions in .NET 4 if the new language features provide a better way of solving the problem.
public static bool CheckIfComPropertyOrMethodExists<T1>(T1 objectToCheck, string propertyOrMethodName)
{
if (CheckIfComPropertyExists(objectToCheck, propertyOrMethodName) == false & CheckIfComMethodExists(objectToCheck, propertyOrMethodName) == false) {
return false;
}
{
return true;
}
}
public static bool CheckIfComPropertyExists<T1>(T1 objectToCheck, string propertyName)
{
return objectToCheck.GetType().InvokeMember(propertyName, BindingFlags.GetProperty, null, objectToCheck, null) != null;
}
public static bool CheckIfComMethodExists<T1>(T1 objectToCheck, string methodName)
{
return objectToCheck.GetType().GetMethod(methodName, BindingFlags.Public | BindingFlags.Instance) != null;
}
帮助文章至今
Helpful articles so far
<一个href="http://stackoverflow.com/questions/5114469/how-to-check-whether-an-object-has-certain-method-property">How检查对象是否具有一定的方法/属性？
<一个href="http://stackoverflow.com/questions/8068449/calling-a-member-of-idispatch-com-interface-from-c-sharp">Calling对IDispatch的COM接口从C＃成员
http://msdn.microsoft.com/en-us/library/ aa909091.aspx
<一个href="http://stackoverflow.com/questions/8069425/implementing-idispatch-in-c-sharp?rq=1">Implementing的IDispatch在C＃
http://msdn.microsoft.com/en-us/magazine/ dd347981.aspx
的http://blogs.msdn.com/b/lucian/archive/2008/10/06/reflection-on-com-objects.aspx
推荐答案
最有可能的COM类还实现了IDispatch接口。然后，您可以使用它的GetIDsOfNames来检查成员是否在类存在。
Most probably the COM class implements also the IDispatch interface. You could then use its GetIDsOfNames to check whether a member exists in the class.
下面有人从C＃调用它：
Here someone calls it from C#:
<一个href="http://stackoverflow.com/questions/8068449/calling-a-member-of-idispatch-com-interface-from-c-sharp">Calling对IDispatch的COM接口从C＃成员
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