Brian Gideon Brian Gideon Add a comment. Active Oldest Votes. Ryan 7, 2 2 gold badges 27 27 silver badges 35 35 bronze badges. Matt Hamilton Matt Hamilton k 60 60 gold badges silver badges bronze badges. It's an easy mistake to make! Brian, welcome to the WPF learning curve. You will come across MANY of these, don't let them get you down. Thanks for the encouragement both of you. WPF is so much different than WinForms I really like what I have seen so far.
Josh Josh Yeah, actually I am using ItemsSource in my real application, but good point nevertheless. A non-type template parameter must have a structural type , which is one of the following types optionally cv-qualified, the qualifiers are ignored :. Array and function types may be written in a template declaration, but they are automatically replaced by pointer to object and pointer to function as appropriate.
A template parameter of the form class Foo is not an unnamed non-type template parameter of type Foo , even if otherwise class Foo is an elaborated type specifier and class Foo x ; declares x to be of type Foo. If the deduced type is not permitted for a non-type template parameter, the program is ill-formed.
For non-type template parameter packs whose type uses a placeholder type, the type is independently deduced for each template argument and need not match:. An identifier that names a non-type template parameter of class type T denotes a static storage duration object of type const T , called a template parameter object , whose value is that of the corresponding template argument after it has been converted to the type of the template parameter.
All such template parameters in the program of the same type with the same value denote the same template parameter object. A template parameter object shall have constant destruction. In the body of the template declaration, the name of a type parameter is a typedef-name which aliases the type supplied when the template is instantiated.
Each constrained parameter P whose type-constraint is Q designating the concept C introduces a constraint-expression E according to the following rules:. In the body of the template declaration, the name of this parameter is a template-name and needs arguments to be instantiated.
The name of a template parameter is not allowed to be redeclared within its scope including nested scopes. A template parameter is not allowed to have the same name as the template name.
In the definition of a member of a class template that appears outside of the class template definition, the name of a member of the class template hides the name of a template parameter of any enclosing class templates, but not a template parameter of the member if the member is a class or function template.
In the definition of a member of a class template that appears outside of the namespace containing the class template definition, the name of a template parameter hides the name of a member of this namespace. In the definition of a class template or in the definition of a member of such a template that appears outside of the template definition, for each non- dependent base class, if the name of the base class or the name of a member of the base class is the same as the name of a template parameter, the base class name or member name hides the template parameter name.
In order for a template to be instantiated, every template parameter type, non-type, or template must be replaced by a corresponding template argument. For function templates , the arguments are explicitly provided, deduced from the context , or defaulted. If an argument can be interpreted as both a type-id and an expression, it is always interpreted as a type-id, even if the corresponding template parameter is non-type:.
The following limitations apply when instantiating templates that have non-type template parameters:. In particular, this implies that string literals, addresses of array elements, and addresses of non-static members cannot be used as template arguments to instantiate templates whose corresponding non-type template parameters are pointers to objects. The template argument that can be used with a non-type template parameter can be any converted constant expression of the type of the template parameter.
A template argument for a type template parameter must be a type-id , which may name an incomplete type:.
A template argument for a template template parameter must be an id-expression which names a class template or a template alias. When the argument is a class template, only the primary template is considered when matching the parameter. The partial specializations, if any, are only considered when a specialization based on this template template parameter happens to be instantiated. See the documentation remarks for details about specifying a non-default namespace for the XML element.
Skip to main content. This browser is no longer supported. Download Microsoft Edge More info. Contents Exit focus mode. Data Template. Data Type Property Reference Is this page helpful? In the Use DataTriggers to Apply Property Values section, we have shown that if you have a collection of the same type of data objects you can create a DataTemplate and then use triggers to apply changes based on the property values of each data object. However, triggers allow you to apply property values or start animations but they don't give you the flexibility to reconstruct the structure of your data objects.
Some scenarios may require you to create a different DataTemplate for data objects that are of the same type but have different properties. For example, when a Task object has a Priority value of 1 , you may want to give it a completely different look to serve as an alert for yourself. In that case, you create a DataTemplate for the display of the high-priority Task objects.
Let's add the following DataTemplate to the resources section:. This example uses the DataTemplate. Resources property. Resources defined in that section are shared by the elements within the DataTemplate. To supply logic to choose which DataTemplate to use based on the Priority value of the data object, create a subclass of DataTemplateSelector and override the SelectTemplate method.
In the following example, the SelectTemplate method provides logic to return the appropriate template based on the value of the Priority property. The template to return is found in the resources of the enveloping Window element. To use the template selector resource, assign it to the ItemTemplateSelector property of the ListBox. The call passes the data object as the item parameter. The DataTemplate that is returned by the method is then applied to that data object.
With the template selector in place, the ListBox now appears as follows:. This concludes our discussion of this example. For the complete sample, see Introduction to Data Templating Sample. Even though the ItemsControl is not the only control type that you can use a DataTemplate with, it is a very common scenario to bind an ItemsControl to a collection. In the What Belongs in a DataTemplate section we discussed that the definition of your DataTemplate should only be concerned with the presentation of data.
In order to know when it is not suitable to use a DataTemplate it is important to understand the different style and template properties provided by the ItemsControl. The following example is designed to illustrate the function of each of these properties. The ItemsControl in this example is bound to the same Tasks collection as in the previous example. For demonstration purposes, the styles and templates in this example are all declared inline.
Refer to the previous section for an example. So far we have only looked at how to bind to and display a single collection.
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