Caché ObjectScript Reference - InterSystems Documentation

Caché ObjectScript CommandsStart ; This routine uses the legacy IF command syntaxSET x=1IF x=1 DO Sub1(x) ; sets $TEST to TRUE (1)ELSE DO Sub2(x)QUITSub1(y) ; a subroutine that evaluates a FALSE IFWRITE !,"hello from subroutine 1"IF y=2 WRITE " - IF in Sub1 was TRUE" ; Set $TEST to FALSE (0)ELSE WRITE " - IF in Sub1 was FALSE"QUITSub2(z) ; another subroutineWRITE !,"hello from subroutine 2"QUITAt first glance, you might expect that Start will call only Sub1 and then exit.In fact, execution of this code produces the following:USER>DO ^Starthello from subroutine 1 - IF in Sub1 was FALSEhello from subroutine 2This unexpected behavior results from the fact the $TEST value is reset in Sub1, that causesCaché to execute the ELSE command in Start. The processing sequence is as follows:1. Caché evaluates the IF command expression in Start as TRUE. It sets $TEST to TRUEand calls Sub1.2. Caché evaluates the IF command expression in Sub1 as FALSE. It sets $TEST to FALSEand then executes the following ELSE command.3. Caché returns to Start when it encounters the QUIT.4. Caché executes the ELSE in Start and performs the DO call to Sub2. It executes theELSE because $TEST was set to FALSE in Sub1, replacing the TRUE value set by theIF command in Start.To produce the expected behavior, you could replace the ELSE in either Start or Sub1with an additional IF. For example, you might recast Start as follows:StartSET x=1IF x=1 DO Sub1(x)IF x'=1 DO Sub2(x)QUITSee Also• GOTO command• XECUTE command• FOR command32 Caché ObjectScript Reference