A.3. Preprocessor statements

This section describes the supported preprocessor statements and their LISA+ semantics. All statements have same syntax and semantics as the corresponding C preprocessor statements.


Define a macro. Macros can have arguments. Converting to strings (# operator) and concatenating (## operator) is supported. The macro is defined in all LISA+ source in the same file that follows the #define statement unless it is explicitly #undefined.

Macros can be redefined several times without warning if the redefinition is identical. Macro expansion is disabled in LISA+ top-level code. See Scope. Macros defined on the LISA+ top-level do not affect conditional statements in the includes and resources section.


Undefine a macro. The macro is undefined in all LISA+ code in the same file that follows this statement. It is not an error if the macro was not defined before this statement.

#if #elif #else #endif

The code enclosed by #if, #elif, #else, or #endif blocks is enabled or disabled depending on the value of the expression following the #if and #elif statements. If the expression evaluates to 0 the code is disabled, for all other values the code is enabled.

Undefined identifiers in the expression have a numerical value of 0. The expression defined(SYM) evaluates to 1 if the preprocessor symbol SYM is defined or 0 if it is not defined.

#ifdef #ifndef

These statements are a shortcut for the #if defined(SYM) and #if !defined(SYM) statements respectively.


Include statements are ignored by the preprocessor. See Scope. However, #include statements in the includes sections of components have the desired effect of making the declarations in the header files visible in the behavior code.


The error message that follows the #error statement is printed. Processing of the LISA+ code by the tool is unsuccessful and the tool performs as if an error has occurred.


The warning message that follows the #warning statement is printed. Processing of the LISA+ code by the tool is successful and the tool performs as normal.

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