COCOS.HLP            COCOS.HLP   1977-07-19  Revised: 1978-07-30

        COCOS - Conditional Compilation in SIMULA
        =========================================

     COCOS is a program to allow one SIMULA source program to
     compile into several differing programs. A preprocessor selects
     statements from the initial source program according to
     selection statements. The initial source program can also be
     compiled directly as one of the versions.

     In the future, some SIMULA compilers may include the interpre-
     tation of the COCOS commands, or some other similar scheme, so
     that no preprocessing is necessary.

     COCOS commands all begin with % in the first character position
     of a source program line. Such lines are ignored by the
     DECsystem-10 SIMULA compiler release 4. (COCOS also accepts
     command lines beginning with COMMENT% as the first non-blank
     text on a source program line.) The source program should not
     contain any lines beginning with % in column 1 or with COMMENT%
     except COCOS command lines.

     The four COCOS commands are:

     %COCOS <variable> = <value>
     %IF <variable>
     %IFNOT <variable>
     %IFEND <variable>                  (%ENDIF is equivalent)

     The commands may, but must not end with semicolon (;).
     There should be no other text on these command lines.

     <variable> can be any valid SIMULA identifier. COCOS variables
     are however always global throughout the whole program and can
     have the same name as other identifiers in the program.

     <value> can only take the values TRUE or FALSE.

     Example:                            Output:
     BEGIN                               BEGIN
     %COCOS GERMAN = FALSE;              outtext("I am.");
     %IF GERMAN;                         outimage;
     outtext("Ich bin.");                END;
     %IFNOT GERMAN;
     outtext("I am.");
     %IFEND GERMAN;
     outimage;
     END;

     With %COCOS GERMAN = TRUE, the output file will include
     "Ich bin." instead of "I am.".

     With each switch is associated three values, the variable name
     (<variable>), the value (<value>) and the condition.

     %IF gives the condition the value YES.
     %IFEND gives the condition the value NEUTRAL.
     %IFNOT gives the condition the value NO.

     No COCOS command lines are copied to the compilable program.
     Other lines are copied only if for all TRUE switches, the
     condition is yes or neutral, and for all FALSE switches, the
     conditiion is no or neutral.

     There can be more than one %COCOS commands for the same
     variable in a processed program. The last command is valid.

     If a %IF... command is encountered with no known value
     for the switch, then COCOS will ask the conversational
     terminal for a value.

     When COCOS is executed, you can give the following command
     string:
     <outfile>=<infile>/<variable1>:<value1>/variable2>:<value2> ...
