Asserting the Ostensibly Unassertable
May 25, 2011 Hey, Ted
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Assertions are great for validating conditions that can be tested with IF, DOW, SELECT, etc., but what about other types of conditions? For instance, can I use an assertion to test that a variable contains valid decimal data? –A Nice Lady (I’m sorry. A nice lady asked me this question in person and I forgot her name.) Yes, it is possible to check for conditions that one cannot test with conditional OPCODES such as IF, but you must use a different method. When something goes amiss, the system loads a five-digit, zoned-decimal status code with a non-zero value. You can access this status through file and program status data structures, but that is so 20th century. The modern way is to use the %STATUS built-in function. The status for invalid decimal data is 907. You can find a complete list of status codes in the RPG reference manual. Here’s one possibility:
H dftactgrp(*no) actgrp(*new)
H bnddir('TOOLKITBD')
D AGoodPgm pr extpgm('AGOODPGM')
D inDecNbr 5p 0
D AGoodPgm pi
D inDecNbr 5p 0
D DecNbr s like(inDecNbr)
D Status s 5s 0
/copy prototypes,assert
/copy qrpglesrc,psds
/free
*inlr = *on;
monitor;
DecNbr = inDecNbr;
on-error;
Status = %status;
endmon;
assert (Status = *zero:
%trimr(psdsProcName) +
' canceled with status ' +
%editc(Status: 'X'));
return;
Here’s another method with more specific error handling:
monitor;
DecNbr = inDecNbr;
on-error 907;
assert (*off: 'Parameter inDecNbr has invalid decimal data');
on-error;
Status = %status;
assert (*off: %trimr(psdsProcName) +
' canceled with status ' +
%editc(Status: 'X'));
endmon;
In each case, the assertion will fail, immediately halting the program, if the inDecNbr parameter does not contain valid decimal data. –Ted RELATED STORY
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