In This Article

Getting Started

This topic covers how to get started using the Python language from the Python Language Add-on, implemented by the PythonSyntaxLanguage class, and lists its requirements for supporting advanced features like parsing and automated IntelliPrompt.

It is very important to follow the steps in this topic to configure the language correctly so that its advanced features operate as expected.

Configure the Ambient Parse Request Dispatcher

The language's parser does a lot of processing when text changes occur. To ensure that these parsing operations are offloaded into a worker thread that won't affect the UI performance, you must set up a parse request dispatcher for your application.

The ambient parse request dispatcher should be set up in your application startup code as described in the Parse Requests and Dispatchers topic.

protected override void OnStartup(StartupEventArgs e) {
	AmbientParseRequestDispatcherProvider.Dispatcher = new ThreadedParseRequestDispatcher();

Likewise it should be shut down on application exit, also as described in the Parse Requests and Dispatchers topic.

protected override void OnExit(ExitEventArgs e) {
	var dispatcher = AmbientParseRequestDispatcherProvider.Dispatcher;
	if (dispatcher != null) {
		AmbientParseRequestDispatcherProvider.Dispatcher = null;

Failure to set up an ambient parse request dispatcher when using the language will result in unnecessary UI slowdown since parse operations will be performed in the UI thread instead of in a worker thread.

Configure the Ambient Package Repository

An ambient package repository should always be set up to ensure that the application is able to use and cache package data from all packages within the Python project's search paths. A Python project (see below) normally adds search paths for the root of your project's .py files, along with external libraries such as the Python standard library's Lib folder. When a search path is added to a project, it will search the cache path to see if the cached data there is up-to-date with the related source package. If not, cache data is added to the package repository via a worker thread.

The ambient package repository should be set up in your application startup code. The FileBasedPackageRepository class is the default implementation of a package repository, which supports the writing of binary package data to a cache folder specified in its constructor, as long as the application has read/write permissions to that folder (usually requires full trust).

protected override void OnStartup(StartupEventArgs e) {
	// Use a path like this if in full trust
	string appDataPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), 
		@"YourCompanyName\YourApplicationName\Package Repository");
	AmbientPackageRepositoryProvider.Repository = new FileBasedPackageRepository(appDataPath);

Failure to set up an ambient package repository provider will result in IntelliPrompt features not working for module internals.

Create the PythonSyntaxLanguage

The next step is to create an instance of the PythonSyntaxLanguage class and configure its project.

This code creates a PythonSyntaxLanguage:

var language = new PythonSyntaxLanguage();

Configure the Python Project

Each language has a IProject registered as a service on it that provides information such as which modules are actively being edited in a SyntaxEditor and the collection of paths to search for external packages.

If you wish to support automated IntelliPrompt for external modules, it is important to add search paths to the project. This tells the resolver where to look for .py files. Note that the resolver will recursively search through child folders of specified paths as long as the folder names are valid Python identifiers.

It is common practice to specify these paths:

  • The root path of your Python project code
  • The path to the Python standard library Lib folder
  • The path to the Python standard library's Lib\site-packages folder
  • The path to any other folders that contain external libraries that are used by code in your project

This code gets the language's default project, and adds several search paths to where external packages can be located and used for IntelliPrompt:

var project = language.GetService<IProject>();

Use the PythonSyntaxLanguage

Next, use the language on the ICodeDocument instances that will be editing Python code.

This code applies the language to a document in a SyntaxEditor, whose instance is in the editor variable:

editor.Document.Language = language;

We recommend reusing your PythonSyntaxLanguage instance among all the documents in your application that are editing Python code. This saves on overall memory usage and reduces load times.

Documents Should Have an Appropriate FileName and Tab Settings

It is a good practice to set the FileName on any document using the language to an appropriate value that uniquely identifies the document's contents. The filename is used as a key to register the module defined in the document with the language's IProject.


If the filename is left empty, relative paths can't be used in from...import statements and some other IntelliPrompt feature might not work properly.

Python also generally prefers that spaces are used in place of tabs for indentation. Set the ITextDocument.AutoConvertTabsToSpaces property to true to force the use of spaces.

This code sets the filename and tab options for a document in a SyntaxEditor, whose instance is in the editor variable:

editor.Document.FileName = @"C:\";
editor.Document.TabSize = 4";
editor.Document.AutoConvertTabsToSpaces = true

Assembly Requirements

The following list indicates the assemblies that are used with the Python syntax language implementation in this add-on.

Assembly Required Author Licensed With Description
ActiproSoftware.Text.Wpf.dll Yes Actipro SyntaxEditor Core text/parsing framework for WPF
ActiproSoftware.Text.LLParser.Wpf.dll Yes Actipro SyntaxEditor LL parser framework implementation
ActiproSoftware.Shared.Wpf.dll Yes Actipro SyntaxEditor Core framework for all Actipro WPF controls
ActiproSoftware.SyntaxEditor.Wpf.dll Yes Actipro SyntaxEditor SyntaxEditor for WPF control
ActiproSoftware.Text.Addons.Python.Wpf.dll Yes Actipro Python Language Add-on Core text/parsing for the Python languages
ActiproSoftware.SyntaxEditor.Addons.Python.Wpf.dll Yes Actipro Python Language Add-on SyntaxEditor for WPF advanced Python syntax language implementations