Implementing assertions in Progress 4GL

Question

What is the best way of implementing assertions using Progress 4GL or WebSpeed?

Answer 1

After some consideration here is my solution to the problem. It works based on the assumption that development environment propath is different from test and production environments and code is always re-compiled for test or production use:

&IF PROPATH MATCHES '*development*' &THEN 
&SCOPED-DEFINE ASSERTION   {1} {2} {3} {4} {5} {6} {7} {8} {9} {10} ~
{11} {12} {13} {14} {15} {16} {17} {18} {19} {20} ~
{21} {22} {23} {24} {25} {26} {27} {28} {29} {30} ~
{31} {32} {33} {34} {35} {36} {37} {38} {39} {40} ~
{41} {42} {43} {44} {45} {46} {47} {48} {49} {50} ~
{51} {52} {53} {54} {55} {56} {57} {58} {59} {60} ~
{61} {62} {63} {64} {65} {66} {67} {68} {69} {70} ~
{71} {72} {73} {74} {75} {76} {77} {78} {79} {80} 


 IF NOT ({&ASSERTION}) THEN 
     MESSAGE "Failed assertion {&ASSERTION} in" PROGRAM-NAME(1).

 IF ({&ASSERTION}) = ? THEN 
     MESSAGE "Unknown value as a result of assertion {&ASSERTION} in" 
              PROGRAM-NAME(1).

&ENDIF

The code is designed to avoid any side effects and works equally well in any execution environment (GUI or ChUI, WebSpeed, AppServer, batch and so on).

1) Save the code as a file called “assert” (without any extension).

2) Place the file into a directory pointed to by PROPATH.

3) Sample usage:

{assert valid-handle(hProc)}
{assert i > 0 and i <= 100}
{assert cExtra begins ‘opt’}  /* note the single quotes */
{assert dtEnd > = dtStart}

As a variation it’s possible to avoid relying on propath altogether by having just an empty include file in test and production environment, the development version will become just:

&SCOPED-DEFINE ASSERTION   {1} {2} {3} {4} {5} {6} {7} {8} {9} {10} ~
{11} {12} {13} {14} {15} {16} {17} {18} {19} {20} ~
{21} {22} {23} {24} {25} {26} {27} {28} {29} {30} ~
{31} {32} {33} {34} {35} {36} {37} {38} {39} {40} ~
{41} {42} {43} {44} {45} {46} {47} {48} {49} {50} ~
{51} {52} {53} {54} {55} {56} {57} {58} {59} {60} ~
{61} {62} {63} {64} {65} {66} {67} {68} {69} {70} ~
{71} {72} {73} {74} {75} {76} {77} {78} {79} {80} 


 IF NOT ({&ASSERTION}) THEN 
     MESSAGE "Failed assertion {&ASSERTION} in" PROGRAM-NAME(1).

 IF ({&ASSERTION}) = ? THEN 
     MESSAGE "Unknown value as a result of assertion {&ASSERTION} in" 
              PROGRAM-NAME(1).

An extra tip is to add an auto-text macro to your editor of choice that will automatically expand into {assert }.