Class RTS_CatchingErrors

java.lang.Object

simula.runtime.RTS_RTObject

simula.runtime.RTS_ENVIRONMENT

simula.runtime.RTS_BASICIO

simula.runtime.RTS_CLASS

simula.runtime.RTS_CatchingErrors

All Implemented Interfaces:

Runnable

public abstract class RTS_CatchingErrors
extends RTS_CLASS

Additional System class CatchingErrors.

This class is used to implement runtime error catching. The basic idea is to enclose the 'inner' statement by a Java try-catch construction and, in the catch section to call a virtual procedure 'onError' to deal with the error situation.

To achieve this, the class CatchingErrors is hand-coded as a standard class.

      class CatchingErrors;
      virtual: procedure onError;
      begin
      -- code: try {
                   inner;
      -- code: } catch(RuntimeException e) {
      -- code:     _CUR=this; // As iff non-local goto here
      -- code:     _onError(e,onError);
      -- code: }
      
      end;  

Usage:

      CatchingErrors begin
          procedure onError(message); text message; begin
              ... treating error
          end;
          ... any error here will cause calling onError
      end;

There are three ways to return from the procedure onError:

1. goto a non-local label.

2. calling terminate_program or error

3. falling through procedure end which has the same effect as ending the prefixed block.

Example: Safe version of getint returns maxint when it fails.

    integer procedure safeGetint(t); text t; begin
        CatchingErrors begin
            procedure onError(message); text message; begin
                safeGetint:=maxint;
            end;
            safeGetint:=t.getint;
        end;
    end;    

Link to GitHub: Source File.

Author:

Øystein Myhre Andersen

Field Summary

Fields inherited from class simula.runtime.RTS_ENVIRONMENT

_STARTTIME, CURRENTDECIMALMARK, CURRENTLOWTEN, EXCEPTION_HANDLER, maxint, maxlongreal, maxreal, minint, minlongreal, minreal, simulaReleaseID

Fields inherited from class simula.runtime.RTS_RTObject

_CORUT, _CTX, _CUR, _DL, _INPUT_LINELENGTH, _JTX, _OUTPUT_LINELENGTH, _SL, _STATE, _SYSIN, _SYSOUT, _USR, startTimeMs

Constructor Summary

Constructors

Constructor	Description
RTS_CatchingErrors(RTS_RTObject staticLink)	Create a new _CatchingErrors instance.

Method Summary

Modifier and Type	Method	Description
void	_onError(RuntimeException e, RTS_PRCQNT match)	This method is called when a RuntimeException occur.
RTS_PRCQNT	_onError_0()	Default virtual match for procedure onError.

Methods inherited from class simula.runtime.RTS_CLASS

_START, run

Methods inherited from class simula.runtime.RTS_BASICIO

terminate_program, toString

Methods inherited from class simula.runtime.RTS_ENVIRONMENT

_char, abs, abs, abs, addepsilon, addepsilon, arccos, arcsin, arctan, arctan2, argv, blanks, Char, clocktime, copy, cos, cosh, cotan, cputime, datetime, decimalmark, DEFEXCEPTION, digit, discrete, draw, edfix, edfix, edit, edit, edit, edit, edit, edit, edtime, edtime, entier, Erlang, error, exit, exp, hash, histd, histo, isochar, isorank, letter, linear, ln, loadChar, log10, lowcase, lowerbound, lowten, max, max, max, max, max, max, max, max, max, max, max, min, min, min, min, min, min, min, min, min, min, min, mod, negexp, normal, Poisson, printStaticChain, printThreadList, randint, rank, rem, sign, simulaid, sin, sinh, sqrt, storeChar, subepsilon, subepsilon, tan, tanh, uniform, upcase, upperbound, waitSomeTime

Methods inherited from class simula.runtime.RTS_RTObject

_GOTO, _JUMPTABLE, _SIM_LABEL, _STM, _TREAT_GOTO_CATCH_BLOCK, _VALUE, arrayValue, BBLK, booleanValue, call, call, charValue, CONC, detach, detach, detach, doubleValue, EBLK, edObjectAttributes, edObjectIdent, floatValue, intValue, isDetachUsed, isQPSystemBlock, objectTraceIdentifier, objectTraceIdentifier, objectValue, procValue, resume, resume, resume, swapCoroutines, sysin, sysout, TRACE_GOTO

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

RTS_CatchingErrors

public RTS_CatchingErrors(RTS_RTObject staticLink)

Create a new _CatchingErrors instance.

Parameters:

staticLink - the static link

Method Details

_onError_0

public RTS_PRCQNT _onError_0()

Default virtual match for procedure onError.

Returns:

nothing

Throws:

RTS_SimulaRuntimeError - always

_onError

public void _onError(RuntimeException e,
 RTS_PRCQNT match)

This method is called when a RuntimeException occur.

Parameters:

e - a RuntimeException

match - virtual match procedure