$IF VERSION THEN $ERROR

[luke]

QB64 1.5 will feature a new metacommand and a new pre-compiler value. The below example shows them both:

Code: [Select]

$IF VERSION < 1.5 THEN
    $ERROR Requires QB64 version 1.5 or greater
$END IF

VERSION evaluates to the QB64 compiler version. $ERROR can be used in a $IF block to give a compilation error with a helpful message to the user if the programmer knows they will be using new features. You could also use $ERROR if you program is Windows-only or Linux-only, for instance. VERSION could also be used to implement a section of code two different ways if you're trying to work around differences in behaviour in QB64 versions.

See wiki for further details.

[SpriggsySpriggs]

Perfect! I love this idea. You guys are great.

[RhoSigma]

Is the build process broken?

Was going to test the $ERROR thing, but the dev-build download is still git e3b9c46 from Jan/27.

Shouldn't it be git f7cd2b2 or 65beb28 from Jan/28 already ??

[FellippeHeitor]

Checking. Thanks for pointing it out.

[RhoSigma]

Just see, it affects the Windows downloads only.

[SMcNeill]

Quick question with all these new error commands:

Since we can generate actual error messages now ( _ERRMESSAGE$, or such, I think), is there some way to set custom messages to go with the codes?

For example, ERROR 5 might give us an error message of “ERROR 5: Illegal Function Call”, but a custom error of 128 would just say, “ERROR 128:”

Is there something like an _CUSTOMERROR$(errNum, errMes$), which an user can use   to set those custom errors?

[FellippeHeitor]

If you have a custom error code it’s likely because you have a custom error handler.

[FellippeHeitor]

@SMcNeill I stand corrected, we already have _ASSERT: http://www.qb64.org/wiki/ASSERT

Code: QB64: [Select]

1. $ASSERTS:CONSOLE
2.  
3. DO
4.     a = INT(RND * 10)
5.     b$ = myFunc$(a)
6.     PRINT a, , b$
7.     _LIMIT 3
8. LOOP UNTIL _KEYHIT
9.  
10. FUNCTION myFunc$ (value AS SINGLE)
11.     _ASSERT value > 0, "Value cannot be zero"
12.     _ASSERT value <= 10, "Value cannot exceed 10"
13.  
14.     IF value > 1 THEN plural$ = "s"
15.     myFunc$ = STRING$(value, "*") + STR$(value) + " star" + plural$ + " :-)"
16. END FUNCTION

It's an on-spot error handler which allows for a custom message.