NetRexx: Current restrictions

Current restrictions

The NetRexx processor is now functionally complete, though work continues on usability and performance improvements. As of this version there are still a number of restrictions, listed below.

Please note that the presence of an item in this section is not a commitment to remove a restriction in some future update; NetRexx enhancements are dependent on on-going research, your feedback, and available resources. You should treat this list as a 'wish-list' (and please send in your wishes).

Short-term restrictions

The following problem may occur in larger methods, with Java 1.0.1, 1.0.2, or 1.1.2 (it seems to have been fixed in later versions):

NetRexxC does not restrict the number of local variables used or generated. However, the 1.0 javac compiler fails with unrelated error messages (such as 'statement unreachable' or 'variable may be uninitialized') if asked to handle more than 63 local variables.

Long term restrictions

The following restrictions are due to the use of a translator, and would probably only be lifted if a direct-to-bytecodes NetRexx compiler were built.

Externally-visible names (property, method, and class names) cannot be Java reserved words (you probably want to avoid these anyway), and cannot start with '$0'.
There are various restrictions on naming and the contents of programs (the first class name must match the program name, etc.).
The javac compiler requires that mutually-dependent source files be on the CLASSPATH, so javac can find the source files. NetRexxC does not have this restriction, but when using javac for the final compilation you will need to follow the convention described under 'Compiling multiple programs', above.
The 'symbols' option applies to all programs compiled together if any of them specify that option.
Some binary floating point underflows may be treated as zero instead of being trapped as errors.
Side-effects of calls to this() and super() in constructors may be seen before the method and method call instructions are traced -- this is because Java does not permit tracing instructions to be added before the call to this() or super().
The results of expressions consisting of the single term 'null' are not traced.

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