van-wijngaarden-switch.a68
1 COMMENT
2
3 @section Synopsis
4
5 Van Wijngaarden's pseudo-switch.
6
7 The following is derived from
8 C.H. Lindsey, A History of Algol 68
9 ACM Sigplan Notices, Volume 28, No. 3 March 1993
10
11 COMMENT
12
13 PRAGMAT quiet regression PRAGMAT
14
15 PR echo "Jumps as row of PROC VOID ... " PR
16
17 # ... But worse! Van Wijngaarden was now able to exhibit his pride and joy -
18 his pseudo-switch [R8.2.7.2]. #
19
20 [] PROC VOID switch = (e1, e2, e3);
21
22 # ... or even ... #
23
24 LOC [1 : 3] PROC VOID loc switch := (e1, e2, e3);
25 loc switch[2] := e3;
26
27 # ... To my shame, I must admit that this still works,
28 although implementations tend not to support it. #
29
30 switch[2];
31
32 print("Can't be here");
33
34 e3: e2: e1: print ("Jumped correctly");
35 newline (standout)
36
37 # A68G correctly executes this code #
