Writing AutoLISP code is typically done in an IDE such as the Visual LISP IDE included with AutoCAD, and this is where most of the work takes place when implementing an OpenDCL application's AutoLISP functions. OpenDCL Studio includes several tools to help programmers with the AutoLISP component of an OpenDCL application.
The OpenDCL Studio control browser provides a context sensitive reference of all supported properties, methods, and events for a specific control. In addition, the control browser makes it easy to copy function signatures to the Windows clipboard for pasting directly into AutoLISP code. The control browser's context sensitive function signatures include the correct control handle for the selected control, thus minimizing typographical errors.
The control browser can be opened by double-clicking on a control in
the OpenDCL Studio workspace. Selecting a property, method, or event
from the list displays syntax and reference documentation in the control
browser's main frame. Pressing the Copy-To-Clipboard button (
)
copies the function signature to the Windows clipboard.
Handling events is the primary task of an OpenDCL application's AutoLISP code, so the process of implementing event handlers has been streamlined as much as possible. In OpenDCL Studio, the property pane's events tab displays the selected event handler function name in a text box below the event list for the selected control. It also displays a complete event handler skeleton function that opens a message box warning that the event handler has not yet been completed. Either the function name or the event handler skeleton function can be selected for copying and pasting into the application's AutoLISP code.
Specific events can be enabled by checking the toggle in front of its name in the event list. Enabling an event exposes two additional ways to incorporate the event handler skeleton function into the associated AutoLISP code. The [Clipboard Copy] button copies the event handler skeleton function to the Windows clipboard for pasting into the code. The [Add to File] button appends the event handler skeleton function directly to the project lisp file. These latter two buttons are displayed only if the "Copy Events to Clipboard" and "Write Events to Lisp File" options, respectively, are enabled in the OpenDCL Studio Tools menu.
Style Guidelines
Best practices for the AutoLISP code that uses an OpenDCL dialog include making event handlers global, and ensuring that the OpenDCL runtime is loaded before any OpenDCL functions are used. Using unique project names (ideally prefixed with a unique developer symbol) helps ensure that name collisions between multiple applications will be avoided. Following consistent control naming conventions helps with project organization and code maintenance. For example, prefixing control names with a three-character control type prefix and naming the control based on its function ("btnOk" for an [OK] button, for example) is a common technique used to make code more readable.
A recommended approach for a typical application is to utilize one AutoLISP file per form, with the lisp code arranged within the file so that the main function is at the top, followed by utility functions, then event handlers.