EditImplementing a VFP Function in the Compiler for .NET
Whitepaper by:
Pertti Karjalainen
Product Manager
Northern Lights Software
Fairfax, CA USA
www.northernlightssoftware.com
If you know VFP, even a little (and even if you don't know much at all about .NET), you, too, can participate in building a fully VFP syntax -compatible compiler for .NET. All you need to know is VFP syntax, you don't need to know C# or VB.NET or any other "foreign" stuff, to get started at least.
Disclaimer: I am in no way affiliated with eTecnologia.net, financially or otherwise. Heck, I don't even know where these guys are located! But the budding technology here is quite amazing and holds a lot of promise for us soon-to-be-orphaned-from-Microsoft VFP developers.
To demonstrate how simple it is for pretty much anyone to help out here, I created a new BETWEEN() -function for .NET that is 100% compatible with the same VFP function. This was one of the functions "Not yet implemented"
http://www.etecnologia.net/Products/VFPCompiler/ImplementedFunctionality.htm.
To differentiate the .NET version from the VFP version for unit testing, I prefaced the function name with "_", but this is by no means a generally accepted way, it just made sense to me. Which is not to say that it might not collide with internal .NET functions or accepted .NET syntax rules.)
And here's what the .NET BETWEEN() -function/procedure looks like:
FUNCTION BETWEEN
LPARAMETERS tu1, tu2, tu3
LOCAL llRetVal
llRetVal = .T.
IF VARTYPE(tu1) = 'U' OR VARTYPE(tu2) = 'U' OR VARTYPE(tu3) = 'U'
?"ERROR: Invalid number of parameters!" && Error handling stub
llRetVal = .F.
ENDIF
IF llREtVal = .T. AND ;
( VARTYPE(tu1) != VARTYPE(tu2) OR ;
VARTYPE(tu1) != VARTYPE(tu3) OR ;
VARTYPE(tu2) != VARTYPE(tu3) ;
)
?"ERROR: Data type mismatch!" && Error handling stub
llRetVal = .F.
ENDIF
IF llRetVal = .T.
llRetVal = .F.
IF tu1 >= tu2 AND tu1 <= tu3
llRetVal = .T.
ENDIF
ENDIF
RETURN llRetVal
&& To call the function, you would do this:
? _BETWEEN(1,2,3)
? _BETWEEN('B','A','C')
etc.
You can actually check this code out for yourself.
1. Copy and paste the function code into:
http://etecnologia.net/onlinecompiler/1.1. Add the function calls to the top of the listing
2. Click "Compile and generate assembly"
3. Download the generated Mydemo.exe to your computer (click the Mydemo.exe -link)
4. Make sure that you have also downloaded and extracted the
VFP Runtime ZIP file from the same page into the same folder where your mydemo.exe is
5. Go to the VFP compiler folder in MS-DOS prompt
6. Type MYDEMO.EXE
7. See the resulting output
It really is that easy. And now we have added one more of the as-of-yet unimplemented functions (BETWEEN()) to the VFP .NET compiler. Granted, this is an easy one, but the majority of the missing functions are about as easy. And the funny thing is that this is both the egg and the hen, since we are writing VFP syntax to implement VFP syntax. Boggles the mind.
And here's my unit test listing, which may serve as a template (to be improved, for sure). This unit test makes sure that the _BETWEEN() function behaves exactly like the VFP's BETWEEN () function under all circumstances.
- Test cases for BETWEEN_E -function (etechnologia replacement for VFP BETWEEN(var1, var2, var3)
- NOTES: Run this test in VFP, not the .NET compiler!
- This test covers the most likely data types: numeric, date and character.
- To complete unit test, we should probably add all of other possible VFP data types.
*Pertti Karjalainen
*Northern Lights Software
*pertti@northernlightssoftware.com
*Original code: 3-26-07
*
CLEAR
SET CONSOLE OFF
SET ALTERNATE TO Test_between
SET ALTERNATE ON
&& all possible test cases (I hope!)
&& numeric:
_BETWEEN(1,1,1) &&same, same, same
_BETWEEN(2,2,2) &&same, same, same
_BETWEEN(3,3,3) &&same, same, same
_BETWEEN(1,1,2) &&small, small, medium
_BETWEEN(1,2,2) &&small, medium, medium
_BETWEEN(1,2,1) &&small, medium, small
_BETWEEN(1,1,3) &&small, small, large
_BETWEEN(1,3,3) &&small, large, large
_BETWEEN(1,3,1) &&small, large, small
_BETWEEN(1,3,2) &&small, large, medium
_BETWEEN(1,2,3) &&small, medium, large
_BETWEEN(2,1,2) &&medium, small, medium
_BETWEEN(2,2,2) &&medium, medium, medium
_BETWEEN(2,2,1) &&medium, medium, small
_BETWEEN(2,1,3) &&medium, small, large
_BETWEEN(2,3,3) &&medium, large, large
_BETWEEN(2,3,1) &&medium, large, small
_BETWEEN(2,3,2) &&medium, large, medium
_BETWEEN(2,2,3) &&medium, medium, large
_BETWEEN(3,1,2) &&large, small, medium
_BETWEEN(3,2,2) &&large, medium, medium
_BETWEEN(3,2,1) &&large, medium, small
_BETWEEN(3,1,3) &&large, small, large
_BETWEEN(3,3,3) &&large, large, large
_BETWEEN(3,3,1) &&large, large, small
_BETWEEN(3,3,2) &&large, large, medium
_BETWEEN(3,2,3) &&large, medium, large
*Characters
_BETWEEN('A','A','A') &&same, same, same
_BETWEEN('B','B','B') &&same, same, same
_BETWEEN('C','C','C') &&same, same, same
_BETWEEN('A','A','B') &&small, small, medium
_BETWEEN('A','B','B') &&small, medium, medium
_BETWEEN('A','B','A') &&small, medium, small
_BETWEEN('A','A','C') &&small, small, large
_BETWEEN('A','C','C') &&small, large, large
_BETWEEN('A','C','A') &&small, large, small
_BETWEEN('A','C','B') &&small, large, medium
_BETWEEN('A','B','C') &&small, medium, large
_BETWEEN('B','A','B') &&medium, small, medium
_BETWEEN('B','B','B') &&medium, medium, medium
_BETWEEN('B','B','A') &&medium, medium, small
_BETWEEN('B','A','C') &&medium, small, large
_BETWEEN('B','C','C') &&medium, large, large
_BETWEEN('B','C','A') &&medium, large, small
_BETWEEN('B','C','B') &&medium, large, medium
_BETWEEN('B','B','C') &&medium, medium, large
_BETWEEN('C','A','B') &&large, small, medium
_BETWEEN('C','B','B') &&large, medium, medium
_BETWEEN('C','B','A') &&large, medium, small
_BETWEEN('C','A','C') &&large, small, large
_BETWEEN('C','C','C') &&large, large, large
_BETWEEN('C','C','A') &&large, large, small
_BETWEEN('C','C','B') &&large, large, medium
_BETWEEN('C','B','C') &&large, medium, large
*Dates
_BETWEEN(DATE(),DATE(),DATE()) &&same, same, same
_BETWEEN(DATE()+1,DATE()+1,DATE()+1) &&same, same, same
_BETWEEN(DATE()+2,DATE()+2,DATE()+2) &&same, same, same
_BETWEEN(DATE(),DATE(),DATE()+1) &&small, small, medium
_BETWEEN(DATE(),DATE()+1,DATE()+1) &&small, medium, medium
_BETWEEN(DATE(),DATE()+1,DATE()) &&small, medium, small
_BETWEEN(DATE(),DATE(),DATE()+2) &&small, small, large
_BETWEEN(DATE(),DATE()+2,DATE()+2) &&small, large, large
_BETWEEN(DATE(),DATE()+2,DATE()) &&small, large, small
_BETWEEN(DATE(),DATE()+2,DATE()+1) &&small, large, medium
_BETWEEN(DATE(),DATE()+1,DATE()+2) &&small, medium, large
_BETWEEN(DATE()+1,DATE(),DATE()+1) &&medium, small, medium
_BETWEEN(DATE()+1,DATE()+1,DATE()+1) &&medium, medium, medium
_BETWEEN(DATE()+1,DATE()+1,DATE()) &&medium, medium, small
_BETWEEN(DATE()+1,DATE(),DATE()+2) &&medium, small, large
_BETWEEN(DATE()+1,DATE()+2,DATE()+2) &&medium, large, large
_BETWEEN(DATE()+1,DATE()+2,DATE()) &&medium, large, small
_BETWEEN(DATE()+1,DATE()+2,DATE()+1) &&medium, large, medium
_BETWEEN(DATE()+1,DATE()+1,DATE()+2) &&medium, medium, large
_BETWEEN(DATE()+2,DATE(),DATE()+1) &&large, small, medium
_BETWEEN(DATE()+2,DATE()+1,DATE()+1) &&large, medium, medium
_BETWEEN(DATE()+2,DATE()+1,DATE()) &&large, medium, small
_BETWEEN(DATE()+2,DATE(),DATE()+2) &&large, small, large
_BETWEEN(DATE()+2,DATE()+2,DATE()+2) &&large, large, large
_BETWEEN(DATE()+2,DATE()+2,DATE()) &&large, large, small
_BETWEEN(DATE()+2,DATE()+2,DATE()+1) &&large, large, medium
_BETWEEN(DATE()+2,DATE()+1,DATE()+2) &&large, medium, large
*--error conditions
_BETWEEN(2,1) &&too few parameters
_BETWEEN(2,'A') &&data mismatch
SET ALTERNATE TO
MODIFY COMMAND TEST_BETWEEN.TXT NOWAIT
RETURN
FUNCTION _BETWEEN
LPARAMETERS tu1, tu2, tu3
LOCAL llRetVal
llRetVal = .T.
IF VARTYPE(tu1) = 'U' OR VARTYPE(tu2) = 'U' OR VARTYPE(tu3) = 'U'
?"ERROR: Invalid number of parameters!" && Error handling stub
llRetVal = .F.
ENDIF
IF llREtVal = .T. AND ;
( VARTYPE(tu1) != VARTYPE(tu2) OR ;
VARTYPE(tu1) != VARTYPE(tu3) OR ;
VARTYPE(tu2) != VARTYPE(tu3) ;
)
?"ERROR: Data type mismatch!" && Error handling stub
llRetVal = .F.
ENDIF
IF llRetVal = .T.
llRetVal = .F.
IF (tu1 >= tu2 AND tu1 <= tu3
llRetVal = .T.
ENDIF
ENDIF
CompareResults(tu1, tu2, tu3, llRetVal) &&Compare the result from this function with that of VFP function
RETURN llRetVal
FUNCTION CompareResults(tu1, tu2, tu3, llRetVal)
?'Function: BETWEEN('+TRANSFORM(tu1)+', '+TRANSFORM(tu2)+', '+TRANSFORM(tu3)+')'
?' Test Result: '+TRANSFORM(llRetVal)
?' VFPFunction: '+TRANSFORM(BETWEEN(tu1, tu2, tu3))
IF llRetVal != BETWEEN(tu1, tu2, tu3)
?' NOT OK!'
ELSE
?' Ok.'
ENDIF
ENDFUNC
So, what are you waiting for? Implement your own "pet" function, test it thoroughly and then send it over to etechnologia.net, so that can be integerated and implemented as a truly .NET compatible VFP function for the entire community!