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40 lines
1.8 KiB
Text
40 lines
1.8 KiB
Text
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'''$LET''' is precompiler command, which is now usable by modern day [[cavemen]] to help include and exclude which sections of code compiles in their program based on OS/bit-size or other predefined conditions.
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{{PageSyntax}}
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:: $LET variable = expression
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* $LET a = 12 sets a precompiler variable "a" to the value of 12. This variable is ONLY valid for the precompiler itself and does NOTHING to affect the values of any variable/constant which might also be called "a" in the program.
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* Variable names can contain numbers, letters, and periods -- in any order! $LET 3.2 = TRUE is a perfectly valid variable and expression.
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* Expressions can contain one set of leading and/or trailing quotes; and any number of numbers, letters, and periods, in any order. $LET 3.2 = "TRUE" is also perfectly, but $LET 3.2 = ""TRUE"" will error. (See the double quotes?)
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''Example 1:''
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{{CodeStart}} '' ''
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{{Cl|$LET}} ScreenMode = 32
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{{Cl|$IF}} ScreenMode = 0 THEN
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{{Cl|CONST}} Red = 4
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{{Cl|$ELSEIF}} ScreenMode = 32 THEN
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{{Cl|CONST}} Red = _RGB32(255,0,0)
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{{Cl|$END IF}}
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{{Cl|COLOR}} Red
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{{Cl|PRINT}} "Hello World"
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{{CodeEnd}}
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Explaination:
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If you look at the code above, you'll see that we have the same CONST defined inside the program. Normally, we get an error if we try to define a CONST more than once, but the $IF condition here is CHOOSING which CONST we want inside our program.
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AS long as Screenmode is 0, the program will exclude the code where CONST Red is defined as color 4. If Screenmode is 32, CONST Red will be defined as _RGB32(255, 0, 0).
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The $LET and $IF statements let us control the code that actually gets compiled, while excluding the other blocks completely.
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''See also:''
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* [[Cavemen]]
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* [[$IF]]
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* [[$ELSE]]
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* [[$ELSEIF]]
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* [[$END IF]]
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{{PageNavigation}}
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