Dynamic Languages

Dynamic languages provide an interactive approach to developing Silverlight-based applications. You can also use them to enable scripting for users of a Silverlight-based application. This QuickStart demonstrates the interactive nature of dynamic languages.

This QuickStart contains the following sections:

• DLR Console Sample
• Using the DLR Console

DLR CONSOLE SAMPLE

The DLR Console is a sample application written in IronPython that enables you to write and execute Python or Ruby code. The following illustration shows the DLR Console.

To try the DLR Console, click the following link and wait a few seconds for it to load. On the Console tab, click once to type code. At the py> prompt, type 1+1 and press ENTER to see the result. Next, type canvas.Background = wpf.RedBrush and press ENTER to change the background color of the right pane. For important information about using the DLR Console, see the Using the DLR Console section.

USING THE DLR CONSOLE

The top left pane of the DLR Console provides tabs for entering code and XAML. The right side of the application is a resizable canvas for the code to manipulate. In the lower-left corner, the language block allows you to select a language. The Python language is selected by default. Sample code statements for the selected language are displayed in the block. You can enter these sample statements, using the Console tab, to create a text block that prints to the console when you click it.

There are three tabs for entering code and loading XAML:

• Use the Console tab to execute code one statement at a time. Code is compiled and executed as soon as a statement is completed. When you write a multiline statement, such as a loop, an if statement, or a method definition, the console prompt changes from a caret to a vertical bar. While you are editing a multiline statement, use the arrow keys to move within the statement. When the statement is complete, press ENTER on an empty line to execute the statement and return to the caret prompt. At the caret prompt, you can use the UP ARROW key to retrieve previously entered statements.
• Use the XAML tab to reset the canvas to its original appearance, or to edit the XAML to change its appearance. Press CTRL+ENTER to load the XAML that is currently shown on the tab.
• Use the Code tab to edit and execute multiple statements. Press CTRL+ENTER to execute the code. The example code that is provided for each language adds a text block control that changes color when the mouse enters and leaves the text block.

When the Console tab executes a Python statement that returns a value, the result of the statement is displayed on the Console tab. Entering a variable name by itself displays the value of the variable. If the variable holds an object reference, a string representation of the object is displayed. The value of Ruby statements is always displayed.

Errors in the dynamic language code that you write are caught, and the error messages are displayed on the Console tab. Errors in the DLR Console itself are displayed at the bottom of the screen.

The tabs provide only basic editing capability:

• Text can be selected by clicking and dragging. The keyboard cannot be used to select text. Selection by double-clicking is not supported.
• The DELETE key is not supported; use the BACKSPACE key instead. Other keys that are not supported include the HOME and END keys.
• There is no Undo functionality.
• To type longer lines of code or to read error messages, use the divider to drag the canvas to the right.
• The Console tab provides limited member name completion for the Python language when the type can be determined. (Variables in Python are not strongly typed.) Complete the name by pressing ENTER. The member name completion list does not include events.

See Also

• Silverlight Dynamic Languages SDK