The Interactive Editor

The Open Dylan environment has a text editor that is specifically designed to make it easy to write and interact with your Dylan code. One of its most unique features is that it actually lets you compile selections of code as you develop your application. This is why we say the editor is interactive.

You can use the editor in one of two styles: Emacs or Windows. Using the editor options, as described in Changing the editor options and layout, you can choose from either an Emacs or Windows style keyboard layout and default settings.

The editor allows you to perform a wide range of operations by using menu commands, as well as keyboard commands. These operations range from simple tasks such as navigating around a file to more complex actions that have been specifically designed to ease the task of writing and working with Dylan code, such as compiling selected blocks of code, setting breakpoints, editing multiple sources, and browsing objects. You can do all of these things while your application is running.

This chapter describes the editor and gives you a general overview of how to use it. Some familiarity with Emacs and Windows usage is presumed.

While basic use of the editor is quite intuitive, by becoming familiar with the menus and options, you can more effectively use the editor to perform advanced operations.

Invoking the editor and displaying files

The editor window lets you read and edit text files stored in your filesystem. You can invoke the Open Dylan editor in a variety of ways:

  • Click the New Text File (

  • Double-click on a file listed in a project window and an editor window opens and displays the file.

  • Click the Edit Source (

  • Choose a file name from the File menu on a project window, an existing editor window, or the main window. (The main window’s File menu only lists files if they have been viewed previously.)

  • Choose Edit Source from the popup (shortcut) menu for an object.

When the editor opens, a buffer containing the text of the current file is displayed, and you can move around it and change its contents as you wish, then save it back to the original file (assuming that you have permission to write to it). Editor window showing the game.dylan file from the Reversi project. shows a file opened in an editor window.


Editor window showing the game.dylan file from the Reversi project.

Display conventions

The editor separates each definition in a source file with a gray line. Printed in the middle of each line is the name of the definition below it. These code separators also appear above top-level expressions wrapped with beginend. A file has to have been compiled for code separators to show.

The code separators are just a visual aid, and are not part of the file itself. If you opened the source file in a different editor you would not see the separators. The compiler also ignores them.

When you add a new definition, or a new beginend top-level form, the code separators will only be updated if you manually refresh the editor window (View > Refresh ), move the cursor past an existing separator, or perform some other operation that forces the editor to redisplay.

If you have opened a source file in the editor by double-clicking on an item in the debugger’s source pane, Open Dylan positions the insertion point at the line containing the problem. If the problem identified by the debugger spans a range of lines, the entire range is highlighted in the editor. Likewise, if the problem is an undefined binding and you have opened the source from the project window’s Warnings tab page, the binding in question is highlighted.

Changing the editor options and layout

By default the editor uses Windows-style defaults and therefore associates each opened file with a new editor window. However, you can change this and edit many different files at once in the same editor by using the View > Editor Options… Display tab page. Alternatively, you can use the Restore tab page to switch to Emacs defaults, which changes this default (and others).

The editor offers a number of different viewing options for the window’s layout.

  • The status bar, located at the bottom of the editor window, lets you examine any output messages from the environment. You can show or hide the status bar using View > Status Bar. This is where you will see messages displayed about your interactive development, such as “Compiling definition…” when you compile a selection.

  • The standard Dylan toolbar can be viewed or hidden with View > Toolbar.

  • The color dispatch optimizations feature, as described in Dispatch Optimization Coloring in the Editor, shows you where and how to optimize your code and is controlled by View > Color Dispatch Optimizations.

The editor window’s context: the active project

In an editor window, the toolbar and menu commands act upon the application of the active project. For instance, the Project, Build, and Application menus are not available in the editor if the source file being edited is not part of the active project — the project whose name is visible in the main window’s drop-down list. See The active project for more details.

Using the editor for interactive development

You will recall from An example interaction with Reversi that we were able to change the shapes of the Reversi game pieces while the application was running simply by providing new definitions in the interactor. Now imagine that you were developing the Reversi application and wanted to interact with it as you coded the sources. The Open Dylan editor allows you to compile pieces of your code and see the results in the running application by using Project > Compile Selection.

In the following example we interact with the Reversi application from an editor window opened on one of the Reversi sources.

Open the Reversi project, and choose Application > Start.

Make some moves on the board.

Open the file board.dylan in the editor by double-clicking it in the reversi project window.

Find the variable definition:

define variable *reversi-piece-shape* = #"circle";

Change the word circle to square, so that the line reads:

define variable *reversi-piece-shape* = #"square";

Select the line of code and choose Project > Compile Selection.

Notice that the status bar says “Compiling region…” and then “*reversi-piece-shape* successfully downloaded”.

Make a few moves on the board.

The new moves and any refreshed area of the board display square game pieces.

Unlike the interactor, which compiles and executes the code you enter in the context of the paused thread to which the debugger is connected, the editor compiles the code you select in the context of a special interaction thread that it chooses automatically. This prevents unnecessary tampering with user threads.

Source control with Visual SourceSafe

To simplify the process of working with files under source control, the Open Dylan editor provides an interface to Microsoft’s Visual SourceSafe, an external source code control system. This section describes the editor interface to Visual SourceSafe. (For information on using Visual SourceSafe, see Visual SourceSafe documentation.)

What is the editor’s source control interface?

A source code control system provides one or more repositories (databases) where developers place source code and related files for a project. Files in the database can be accessed by several developers simultaneously by copying them from the database to their local machine. A developer can “check out” one or more files from the database in order to make changes and, when finished, “check in” the updated files for use by other developers. The database maintains a history of the changes made to each file, making it possible to retrieve older versions if necessary. It also provides mechanisms to resolve conflicts when two or more developers are making changes to the same files at the same time.

The Open Dylan source control interface provides access to a subset of Visual SourceSafe features, which are described in The SourceSafe menu commands. To perform more complex actions, you must use the source control system’s native interface.

Open Dylan detects a Visual SourceSafe installation on a machine and automatically makes its interface to source control available by creating an additional SourceSafe menu on editor windows (see The SourceSafe menu on a Open Dylan editor window.). Therefore, you must have Visual SourceSafe installed in order to see the SourceSafe menu.


The SourceSafe menu on a Open Dylan editor window.

The SourceSafe menu commands

The SourceSafe menu provides the following commands:

Get Latest Version…

Copies the latest version of a file in the database onto the developer’s machine.

Check Out…

Copies the latest version of a file in the database onto the developer’s machine. In addition, the database is updated to note that the file is being edited by the developer.

Check In…

Copies a file from the developer’s machine back into the database, creating a new version of the file, and notes that the file is no longer being edited by the developer.

Undo Check Out…

Notes in the database that a file is no longer being edited by the developer and does not change the latest version of the file. In addition, the latest version of the file is copied from the database onto the developer’s machine; any changes the developer may have made to the local copy of the file are abandoned.

Merge with Source Control…

Merges the changes made by the developer to the local copy of a file with the latest version of the file in the database and replaces the local copy of the file with the merged edition; the file remains checked out by the developer.

Add to Source Control…

Creates the first version of a file in the source control database using the copy on the developer’s machine as the initial content.

Remove from Source Control…

Removes a file and its history from the database.

Show History…

Displays the list of changes made to a file as recorded in the database.

Show Differences…

Compares the latest version of a file in the database against a copy on the developer’s machine and displays the differences, if any. This command can be used to check to see if others may have made changes to a file that should be merged into the developer’s copy before it is checked into the database.

Using the editor’s source control interface

The first time you choose one of the SourceSafe menu items, the editor prompts you for the name of the SourceSafe database, as shown in The Select Database dialog..


The Select Database dialog.

Your site’s Visual SourceSafe administrator supplies the name of your SourceSafe database. (The Open Dylan interface offers the name of the last database used in the Visual SourceSafe explorer as the default.)

The editor then requests the identity of the file (or files) to be manipulated by a source control operation, as shown in The Select Project and File dialog..


The Select Project and File dialog.

SourceSafe organizes its database into a hierarchical collection of projects. Each project can hold both files and projects (in other words, subprojects). The project named $/ refers to the root of the SourceSafe database. In The Select Project and File dialog. the developer has selected a project three levels below the root.

When using Visual SourceSafe, you may omit the file name in all operations (except for SourceSafe > Add to Source Control… and Remove from Source Control… ) to cause the operation to be performed on all files in the project. For instance, to check out all the files in a project, leave the File field empty in the Select Project and File dialog.

The Reason field is provided mainly as a convenience. Not all operations prompt you for a Reason; in such cases the dialog only asks for the project and file names. When a Reason is requested, it is optional and may be left blank.