VSTO在VBA：AddIn.Object返回Nothing（空）有时VBA、VSTO、AddIn、Nothing

2023-09-07 10:09:43 作者：爱是回不去的旅行

由于：

系统VSTO加载项的覆盖对象RequestComAddInAutomationService（）返回一个被称为外观在我的场景类的一个实例。在VBA宏在Excel 2007中它访问 AddIn.Object 获得外观和使用它。系统很多次，在那里这工作完全正常。有几次在哪里出了蓝色，这似乎并没有工作。 A VSTO Add-In An override object RequestComAddInAutomationService() which returns an instance of a class which is called Facade in my scenario. A VBA macro in Excel 2007 which accesses the AddIn.Object to get the Facade and uses it. A plenty of times where this works perfectly fine. A couple of times where out of the blue, this doesn't seem to work.

更新：原来，这是有问题的特定用户。她拥有它的时候，别人也永远不可能拥有一切（？从来不说从来没有）

在此几次我知道

错误：对象变量或With没有设置块变量

Error: Object variable or With block variable not set

在code中的线，试图访问外观的属性。总之，我可以告诉你，code。在 RequestComAddInAutomationService（）没有任何出错的魔法在里面，和VBA code访问外接已经采取了从网页看起来不错，太。在更长的版本尚未到来，对于那些谁就会花时间来阅读： - ）

at the line of code which tries to access a property of Facade. In short I can tell you that the code in RequestComAddInAutomationService() doesn't have any error-prone magic in it, and the VBA code to access the add-in has been taken from the web and looks fine, too. The longer version is yet to come, for those who'll take the time to read it :-)

问：有没有人有一个线索，为什么会发生这种情况？它是一个Excel的问题？

详细的承诺：

MyAddIn.cs：

MyAddIn.cs:

public partial class MyAddIn
{
    public Facade Facade { get; private set; }

    protected override object RequestComAddInAutomationService()
    {
        if (this.Facade == null)
            this.Facade = new Facade(Controller.Instance);

        return this.Facade;
    }
}

Facade.cs：

Facade.cs:

[ComVisible(true)]
[Guid("1972781C-A71A-48cd-9675-AE47EACE95E8")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface IFacade
{
    // some methods
}

[ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class Facade : IFacade
{
    private Controller Controller { get; set; }

    public Facade(Controller controller)
    {
        this.Controller = controller;
    }
}

外观有一些方法，但不是一个单一的领域。

Facade has some methods but not a single field.

Controller.cs：

Controller.cs:

public class Controller
{
    private static Controller instance = null;
    public static Controller Instance
    {
        get
        {
            if (instance == null) instance = new Controller();
            return instance;
        }
    }

    private Controller() { }
}

控制器有一些私人领域。由于字段赋值在创建时会执行，我回顾了他们。他们中的大多数都不会在所有的初始化，或者它们设置为空，所以构造函数做几乎没有。

Controller has some private fields. Since the fields assignments are executed on creation, I reviewed them. Most of them are not initialized at all, or they are set to null, so the constructor does virtually nothing.

在VBA code：

Dim addin As Office.COMAddIn
Dim automationObject As Object

Set addin = Application.COMAddIns("My AddIn")
Set automationObject = addin.Object

Dim oResult As Object
Set oResult = automationObject.SomeMethodThatReturnsAnObject()

最后一行就是错误发生。虽然叫方法返回一个对象，我是pretty的肯定，它不能是错误的根源：如果参考返回信息空，那么该语句将简单地计算结果为设置oResult =无这仍然是有效的。 VBA而引发此类型的错误，每当一个方法上的参考是没有，这是 automationObject 在执行我的案例。

The last line is where the error happens. Although the method called returns an object, I am pretty sure that it cannot be the source of the error: If the reference returned was null, then the statement would simply evaluate to Set oResult = Nothing which is still valid. VBA rather throws this type of error whenever a method is executed on an reference that is Nothing, which is automationObject in my case.

在另一方面，如果该加载项是根本不存在的 Application.COMAddIns（...）将引发的索引列界的错误，我已经看到过。

On the other hand, if the add-in wasn't there at all, the Application.COMAddIns(...) would raise an index out of bounds error, I've seen that before.

VSTO在VBA：AddIn.Object返回Nothing（空）有时VBA、VSTO、AddIn、Nothing

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