Limitations

The current implementation is still very preliminary. It has the following limitations:

1. Nonlinear constraints. DJ does not allow the users to write nonlinear constraints and thus cannot be used to draw many complicated charts. Without nonlinear constraints, it is impossible, for example, to place components along a circle.

2. Float constraints. Constraints over floats are not supported now. Due to this limitation, DJ cannot be used in many engineering fields. Floats are required in many CAD applications.

3. Optimization constraints. In many optimization problems, it is required to find a solution such that a function is minimized or maximized. This functionality is not supported in the current version.

4. System integration. A generated Java program is an applet into which all components are placed. Due to this flat structure, it is difficult to write event handlers for components in the generated Java program, and is thus difficult to integrate the generated Java program with other applications. In the beginning, we tried to translate a DJ program into a Java program such that the class hierarchy is kept as it is: The main class is translated into an applet and all other classes are translated into panels. However, because a panel may hide other panels or components, we failed to find a method to have panels placed such that no components are hidden. To make generated Java programs easy for integration, we still have to keep the class hierarchy of the original DJ program.

5. Dynamic constraints. All constraints in DJ are static in the sense that they will not be rechecked when some attribute values of components are updated. To check constraints dynamically is not an easy task, because we need to have a constraint solver in the Java run-time system.

6. Graphical environment for DJ. A GUI environment is required that in which a user can compile programs and view solutions.