Appendix: Miscellany

Importing and exporting data: sys.exp is monadic and takes any A+ data object as its argument, returning an encoded character vector. sys.imp is also monadic and takes any result of sys.exp as its argument and returns the decoded data object as its result. Results of sys.exp are convenient for writing data to files or sending it to another Unix process.

Bus error: The A+ interpreter attempted to read from an address outside your area, or an attempt was made to read or write without regard to address alignment. If a [error] : bus (or a  : bus)  error occurs, the application should be restarted. If the error can be recreated, please contact us to look into it. See `busexit.

Segv error: The A+ interpreter attempted to write in an address outside your area. If a [error] : segv (or a  : segv) error occurs, the application should also be restarted, just as for a bus error, and the error reported to the A+ development group, email id aplusdev. See `busexit.

Process `a' illegal instruction: This message is most commonly caused by a bus or segv error, and indicates that you continued your session after a bus or segv error occurred. The application should be restarted and, if you didn't continue after a bus or segv error, please contact us so that we can look into it.

If an error is signalled by a program, as opposed to occurring in a primitive function or operator, the stack variables are not likely to be helpful. In particular, if an error is signalled from within adap, the stack variables will be meaningless, since there is no point in adap to suspend at.

The system context function, sys.getdomainname{}, if successfully executed, returns a character vector containing the NIS domain name of the current host; otherwise, it returns Null.


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