分离视图，命令演示（文本，图标）和命令逻辑（执行，CanExecute）

Question

If TL;DR: see the last paragraph.

Pure WPF "suggests" putting presentation (controls, text, icons) into views and command logic (Execute, CanExecute methods) into code-behind. Besides putting logic both into views ( CommandBindings ) and code-behind being a frowned upon practice, it doesn't help at all with XAML duplication : text, icons, large icons, hints, and numerous other properties have to be duplicated every time a command is used: for main menu, for context menu, for toolbar button, for ribbon button and other controls.

Looks like the first problem (truly separating views and logic) is solved by DelegateCommand , RelayCommand and approaches like that. Command logic is moved into ViewModels (or Controllers in case of MVVMC), code-behind is clean, no CommandBindings and other nonsense in views.

However, I can't find a commonly accepted solution to the presentation duplication problem. I want to separate command presentation (text, icons) and command logic ( Execute , CanExecute methods). All code I could find either puts presentation into code (by creating a RoutedCommand with additional properties like Label and Icon ), or puts code into presentation (that is, handlers into views and code-behind). I don't like either. I think presentation should be completely in XAML, and code should be completely in CS (either in ViewModel or Controller).

Question: how to separate views (XAML with controls which reference commands), presentation of commands (labels, icons etc. for every command) and logic of commands (C# code for Execute , CanExecute etc. in ViewModels or Controllers)?

Answer 1

There is no built-in solution to this problem, your're going to have to roll-up your sleeves and create the required structure yourself.

In a recent project I worked on, I did exactly this. I created a concept called an 'action' which supplements the WPF ICommand with other visual properties. It was something like this ...

interface IAction
{
  ICommand Command { get; }
  string DisplayText { get; }
  string ToolTipText{ get; }
  URI Icon { get; }
}

The application contained a collection of Action instances. These could then be bound to menus, toolbars etc ... allowing the same Action instance to be re-used with various different presentation styles. It is all fairly straightforward MVVM stuff!