SCI Programming Language/Definitions

Official SCI Documentation

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Definitions
Author: Jeff Stephenson

 

define

The define statement allows you to define a symbol which will stand for a string of text:

(define symbol lots of text)

will replace symbol, wherever it is encountered as a token, with lots of text and then continue scanning at the beginning of the replacement text. Thus, if we write:

(define symbol some text) (define same even more)

then:

(symbol)

will become:

(some text)

which then becomes:

(even more text)

enum

The enum statement eases the definition of the various states of a state-variable. Say you want to walk an actor from the door of a room across the floor, up the stairs, and through another door. You have a state-variable called actor-pos which will take on a number of values. These could be defined with defines as follows:

Code:

(local	actorPos
   define AT FRONT DOOR		0)
   define IN ROOM		1)
   define ON STAIRS		2)
   define TOP OF STAIRS		3)
   define UPPER DOOR		4)
)

or you could get the same result with enum:

Code:

(local actor-pos
   (enum
      AT FRONT DOOR
      IN ROOM
      ON STAIRS
      TOP OF STAIRS
      UPPER DOOR
   )
)

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Enum defaults its first symbol to O. If you want a different starting value, put it right after the word enum:

Code:

(enum 7
   AT FRONT DOOR
   IN ROOM
   ON STAIRS
   TOP OF STAIRS
   UPPER DOOR
)

sets AT FRONT_ DOOR to 7, IN _ ROOM to 8, etc.

The value of an enum may also be defined by an expression, as follows:

Code:

(enum
   AT FRONT DOOR = (+ AT REAR DOOR 1)
)

Note: Define and enum statements may be included within both global and local variable definitions.

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