当我使用区分大小写的语言时，如何解决COM中不区分大小写的冲突名称

Question

This question is an extension of this article .

In the same case, I created a instance of WMP ActiveX by its ProgID .

protected const string WMP_PROG_ID = "WMPlayer.OCX.7";

private dynamic _wmp;

protected virtual bool init(){
    try{
        _wmp = Activator.CreateInstance(Type.GetTypeFromProgID(WMP_PROG_ID));
    }
    catch{ return false; }
    return connectEvent();
}

According the MSDN document, there are an Error event and an error property in WMPlayer object. So, I try to attach events like this way.

protected bool connectEvent(){
    try{
        _wmp.PlayStateChange += new StateHandler(_wmp_PlayStateChange);
        //_wmp.Error += new Action(_wmp_ErrorEvent);
    }
    catch { return false; }
    return true;
}

protected void _wmp_PlayStateChange(WMPlayerState state){
    //do something I like
}

protected void _wmp_ErrorEvent(){
    //do some error handling
}

If I keep //_wmp.Error += new Action(_wmp_ErrorEvent) commented, there's no compile error and PlayStateChange works pretty good.

However, if I remove the comment mark, there's a runtime exception. Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: can not apply operator "+=" between 'System.__ComObject' and 'System.Action'

It seems the two "error" are conflicted because COM is case insensitive. How can I solve it? My goal is that attach to "Error" event without using AxWindowsMediaPlayer.

Answer 1

I ran in to a very similar problem as you but mine was with Size . The strongly typed ActiveX control redefined Size so I needed to cast it back to Control when the forms designer wanted to size the control on my form.

((Control)this.axLEAD1).Size = new System.Drawing.Size(298, 240);

If you can get a strongly typed class for the com object (by adding a reference or using tlbimp.exe ) you may be able to cast to the strongly typed com object instead of __ComObject and have it use the correct method.