Error History  -  error information display

by Alex Hayward


Error History is a debugging tool which records the details of the previous three system errors. Line numbers or addresses in the error messages are preserved and can then be used later to locate the error. For example, suppose that you are debugging a program which fails with an Address Exception error. Normally you would need to make a note of the address at which the error occurred before cancelling the error box, but by using Error History the details of the error, and of the previous two errors, will remain visible on the screen. You can then refer to this while you are examining the program.

Error History can be run from the RISC User menu system, or by double-clicking on its icon in a directory viewer. An icon is installed on the icon bar. Clicking Menu on this icon brings up a menu with twooptions, Info and Quit, which perform their usual functions.

Clicking Select on the icon bar icon opens the main window. This has three identical sections within which the error details are displayed. These are firstly the text of the error, then the error number, and finally the source of the error (i.e. the module within which the error occurred, e.g. the Wimp, the OS etc.). The latter may help you to determine which SWI call returned an error.

Customising the application
The error source is decoded by the procedure PROCersr, which looks at the error number and attempts to relate it to a list of known error block numbers; for example, errors less than &100 are generated by the OS, while errors between &280 and &2BF are generated by the Wimp. You can add further error sources to the list by simply adding lines of the format:
IF !erb>x AND !erb<y ersr$="source":ENDPROC
where x and y are the lower and upper limits of the error block, and source is the name of the error source, e.g. "Wimp".


Copyright  RISC User 1994
