Question

C# 3.5 Winforms…

So I’ve recently discovered the IExtenderProvider and how it can be used to extend controls with additional properties.

In a prototype project that I setup i put a break point on the ‘set’ method for my extendee property and as the form loads I could see the ‘set’ method executing for every control on the form; which is exactly what I wanted. Following the successful prototype I implemented the extender component into my main project. All the forms in my project inherit from a base form which I’ve added my extender component to. On the base form I set the modifier of the extender component to public so that its accessible by the form inheriting this base form.

Doing the same thing before i added a break point on the ‘set’ method for my extendee property but the method doesn’t execute for the controls in the form (but only for the controls in the base form). HELP!

I should probably add at this point that i’ve source controlled my forms and so most of them are checked-in (ie lock from modification). For the forms that I’ve checked out and modified the provider property; I’ve noticed in the designer file that all controls have an additional statement which calls the ‘set’ method of the provider property.

this.MyProvider1.SetMyProperty(this.txtTextBox1, false);

Am I right in thinking that for the extender component to work it has to physically modify the designer file or should it be able to cope with locked files and therefore call the set method dynamically? I guess if it does have to modify the designer file then this isn’t a problem for new forms or forms that get modified after the extender component was added to the project – but it would be problem when you have 101 forms all locked by source-safe…

I’d appreciate any thoughts…

Answer 1

At what point does the extender provider (IExtenderProvider) extend the ‘type’ (in my case a winforms control) that the extender was intended for; at design time or at run time?

The designer is responsible for showing you the properties of the extender in the property editor
Method bool CanExtend(object) from the IExtenderProvider interface

Am I right in thinking that for the extender component to work it has to physically modify the designer file or should it be able to cope with locked files and therefore call the set method dynamically?

It has to physically modify the designer file, and write the extended properties there

I guess if it does have to modify the designer file then this isn’t a problem for new forms or forms that get modified after the extender component was added to the project – but it would be problem when you have 101 forms all locked by source-safe…

This is is not a problem for new forms, and not for old forms.
If you want to set some extended properties, open the old form and set the extended properties (a check out of the file is necessary)