Initial data commit

Task/Exceptions/ALGOL-68/exceptions-2.alg

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+#!/usr/bin/a68g --script #
+
+MODE OBJ=UNION(REF INT, REF REAL, REF STRING,# etc # VOID);
+
+OP OBJIS = (OBJ a,b)BOOL: # Are a and b at the same address? #
+  CASE a IN # Ironically Algol68's STRONG typing means we cannot simply compare addresses #
+    (REF INT a): a IS (b|(REF INT b):b|NIL),
+    (REF REAL a): a IS (b|(REF REAL b):b|NIL),
+    (REF STRING a): a IS (b|(REF STRING b):b|NIL)
+  OUT FALSE
+  ESAC;
+
+PR READ "prelude/event_base(obj).a68" PR;
+NEWEVENTOBJ obj eventa := SKIP;
+NEWEVENTOBJ obj eventb := SKIP;
+NEWEVENTOBJ user defined exception := SKIP;
+
+# An event can be continued "mended" or break "unmended" #
+PROC found sum sqs continue = (OBJ obj)BOOL: ( print("."); TRUE); # mended #
+PROC found sum sqs break = (OBJ obj)BOOL: (found sq sum sqs; FALSE); # unmended #
+
+INT sum sqs:=0;
+REAL x:=111, y:=222, z:=333;
+
+SCOPEOBJ obj scope reset := obj on((sum sqs, x,y,z), (obj eventa,obj eventb), VOID:found sq sum sqs);
+
+# An event handler specific to the specific object instance: #
+#SCOPEOBJ obj scope reset := obj on eventb(sum sqs, VOID:found sq sum sqs);#
+
+# Or... An "obj any" event handler: #
+# SCOPEOBJ obj scope reset := found sum sqs break ON obj eventb; #
+
+# Raise the "event eventb" on an object: #
+  FOR i DO
+    sum sqs +:= i*i;
+    IF sum sqs = 70*70 THEN # 1st try to use an instance specific mend on the object #
+      obj raise(sum sqs, obj eventb, "Found a sq sum of sqs") FI; # OR ... #
+    IF sum sqs = 70*70 THEN "Found a sq sum of sqs" RAISE obj eventb FI; # OR ... #
+    IF sum sqs = 70*70 THEN RAISE found sum sqs break FI # simplest #
+  OD;
+  RESET obj scope reset # need to manually reset back to prior handlers #
+
+# Catch "event eventb": #
+EXIT found sq sum sqs:
+  print(("sum sqs:",sum sqs, new line)); # event eventb caught code here ... #
+  RESET obj scope reset;
+
+  "finally: raise the base unmendable event" RAISE obj eventb