\ Anonymous "things"                                  NLM900607 These screens were part of my article Anonymous "Things,"       published in Forth Dimensions, May/June 1990. They permit you   to create and use anonymous words of any kind, including        variables, constants, and colon definitions.                                                                                    The letter N in these words stands for "Nameless." I couldn't   use A because A: is already defined in F83.                                                                                     N: is more complicated than the others. It was necessary to     redefine : and ;                                                                                                                Screen 2 defines NVARIABLE, NCONSTANT, N:, and IMPERSONATOR. It is the only required screen. Screen 3 has NCODE, NCREATE, and   NDOES>. Screen 7 maintains compatibility with an older version.                                                                 \ ANONYMOUS "THINGS"  (Load screen)                   NLM900607  2  LOAD                 \ Basic definitions                     3  LOAD                 \ NCODE NCREATE  NDOES>                                                                                \  Examples and tests                                            4  LOAD                 \ Create & test N2CONSTANT              5  LOAD                 \ Create & test 3CONSTANT & N3CONSTANT  6  LOAD                 \ Create & test 4CONSTANT & N4CONSTANT \  7  LOAD                 \ Compatibility with previous version\  8  LOAD                 \ Test small n display               cr .( Anonymous "things" loaded.)                                                                                                                                                                                                                                                                                                                                                               \ ANONYMOUS "THINGS"  (BASIC DEFINTIONS)              NLM900607 VARIABLE DEBUGGING                  DEBUGGING OFF               : PSEUDONAME DEBUGGING @ IF 129 C, 238 C, THEN ;                : NVARIABLE ( ... addr) PSEUDONAME HERE ['] >IN @  , 0 , ;      : NCONSTANT ( n ... addr)                                           PSEUDONAME HERE >R ['] B/BUF @ ,  , R> ;                    : IMPERSONATOR CREATE ['] CRASH ,  IMMEDIATE                         DOES> @  STATE @  IF , ELSE EXECUTE  THEN ;                IMPERSONATOR C-PART                                             IMPERSONATOR D-PART                                             NVARIABLE IS C-PART                                             : N: PSEUDONAME HERE C-PART ON                                       ['] NVARIABLE @  , !CSP CURRENT @ CONTEXT ! ] ;            : : C-PART OFF [COMPILE] : ;                                    : ; C-PART @ IF ?CSP COMPILE UNNEST [COMPILE] [ C-PART OFF           ELSE [COMPILE] ; THEN ; IMMEDIATE                          \ NCREATE NDOES> NCODE                                NLM900607 : (NCREATE) PSEUDONAME HERE 2 ALLOT ;                           : N(;CODE) R> OVER ! ;                                          : (NDOES>) COMPILE N(;CODE)  232 C, 333 HERE 2+ - , ; IMMEDIATE                                                                 : NCREATE COMPILE (NCREATE) COMPILE >R ; IMMEDIATE              : NDOES> COMPILE R> [COMPILE] (NDOES>) ; IMMEDIATE                                                                                                                                              : NCODE  PSEUDONAME HERE DUP 2+ , CONTEXT @ AVOC ! ASSEMBLER ;                                                                                                                                                                                                                                                                                                                                                                                                  \ Defining and Testing N2CONSTANT by Method 1         NLM881223 \ Step 1. Define a 2CONSTANT                                    0. 2CONSTANT ZERO                                               \ Step 2. Use the defined 2CONSTANT to define others.           : N2CONSTANT ( -- addr) PSEUDONAME                                 HERE >R [ ' ZERO @ ] LITERAL , , , R> ;                                                                                      \ Testing                                                       5. N2CONSTANT   IS C-PART                                       : TEST4  C-PART D. ;                                            CR .( SHOULD PRINT 5    ) TEST4 CR                                                                                                                                                                                                                                                                                                                                                              \ CREATING A NEW TYPE OF ANONYMOUS "THING" (Method 1) NLM881223 \ Defining 3CONSTANT and N3CONSTANT                             \ Step 1. Define the "Create" part as an anonymous.             N: , , , ; IS C-PART                                                                                                            \ Step 2. Define a normal creator.                              : 3CONSTANT CREATE C-PART  DOES>  DUP 2+ 2@ ROT @ ;                                                                             \ Step 3. Create an example.                                    0 0 0 3CONSTANT 3ZEROES                                                                                                         \ Step 4. Use the example as a basis for the anonymous creator. : N3CONSTANT PSEUDONAME  HERE >R ['] 3ZEROES @ , C-PART R> ;    CR .( SHOULD PRINT 0 0 0  ) 3ZEROES . . . CR                    1 2 3 N3CONSTANT IS C-PART  CR .( SHOULD PRINT 3 2 1  )            C-PART . . . CR                                              \ CREATING A NEW TYPE OF ANONYMOUS "THING" (Method 2) NLM881223 \ DEFINING 4CONSTANT AND N4CONSTANT                             \ Write CREATE and DOES> parts; assign them to impersonators    N: ( n4 n3 n2 n1 -- ) 2SWAP , , , , ;  IS C-PART                N: ( adr -- n4 n3 n2 n1) DUP 2@ ROT 4 + 2@ ;  IS D-PART                                                                         \ Write the definers according the the following set formula    : 4CONSTANT  CREATE C-PART  DOES> D-PART ;                      : N4CONSTANT NCREATE C-PART NDOES> D-PART ;                                                                                     \ Testing                                                       1 2 3 4 4CONSTANT XYZ                                           5 6 7 8 N4CONSTANT IS C-PART                                    CR .( SHOULD PRINT 4 3 2 1   ) XYZ . . . . CR                   CR .( SHOULD PRINT 8 7 6 5   ) C-PART . . . . CR                                                                                \ Compatibility with previous version (ANON etc.)     NLM900607 IMPERSONATOR ANON                                               : MAKEANON NVARIABLE IS [COMPILE] ANON ;                        : ANON+ [COMPILE] [ [COMPILE] ANON + [COMPILE] LITERAL ] ;          IMMEDIATE                                                   : STORESTACK ( n -- ) 2* BOUNDS ?DO I ! 2 +LOOP ;                                                                                                                                                                                                               \S Testing                                                      makeanon 10 allot                                               2 anon 2+ !                                                                                                                     : xyz  [ 2 ] anon+ ? ;                                          CR .( SHOULD PRINT 2 ) XYZ                                                                                                      \ TESTING SEE AND DEBUG                               NLM881222 NVARIABLE IS C-PART                                             : TEST7 C-PART OFF C-PART ? ;                                   CR .( SHOULD PRINT 0 ) TEST7 CR                                                                                                 CR .( Result will depend on mode ) CR                           .( MAY SHOW GARBAGE) CR                                         .( MAY SHOW "n" FOR ANONYMOUS ) SEE TEST7 CR                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    \ ANONYMOUS "THINGS"  (BASIC DEFINTIONS)              NLM900607 DEBUGGING, PSEUDONAME If the variable DEBUGGING is on, then     anonymous things have a pseudoname field of lower case n.       NVARIABLE NCONSTANT N: Define an anonymous thing and leave its  cfa on the stack.                                               IMPERSONATOR Something like DEFER but compiles or executes,     according to the contents of STATE. Example:                    IMPERSONATOR TEMP  \ define an impersonator                     3 NCONSTANT        \ Define an anonymous constant. Note that it                    \ has no name. The cfa is left on the stack  IS TEMP            \ Make TEMP act like a constant with the                                                                                        \ value 3.                                   : FOO TEMP . ;     \ FOO will display 3                         NVARIABLE IS TEMP  \ TEMP is now a variable, but FOO still                         \ displays 3                                 \ NCREATE NDOES> NCODE                                NLM900607 NCODE  Use with END-CODE to create an anonymous code            definition. Example:                                                                                                            NCODE AX POP NEXT END-CODE   IS TEMP                            \ The impersonator TEMP now has the same action as DROP                                                                         NCREATE NDOES> Create a new anonymous class. See examples on    screens 4-6                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     \ TESTING ANONYMOUS WORDS                             NLM881201 IMPERSONATOR TEMP Create an impersonator                        3 NCONSTANT   IS TEMP  Create an anonymous constant with the      value 3 and assign it to TEMP. TEMP will act as if you had      defined it in the usual way by 3 CONSTANT TEMP -- the assign-   ment will remain in effect until TEMP is given a new action.                                                                  NVARIABLE  IS TEMP  Define an anonymous variable, and assign      it to TEMP. TEMP will act as if you had written VARIABLE TEMP                                                                 N:  ." HELLO " ; IS TEMP  Create an anonymous colon definition    and assign it to TEMP. TEMP will now act as if you had          redifined it by writing : TEMP ." HELLO " ;                                                                                                                                                                                                                   \ A WORD ABOUT IMPERSONATORS                          NLM900607                                                                 The number of impersonators required is determined by how       many need to be active at the same time. Three or four are      usually enough. Extras may improve readability.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 \ TESTING ANONYMOUS WORDS                             NLM881201 IMPERSONATOR TEMP                                               3 NCONSTANT   IS TEMP                                           : TEST1  TEMP . ;                                               CR .( SHOULD PRINT 3   )  TEST1  CR                                                                                             NVARIABLE  IS TEMP                                              : TEST2  4 TEMP !  TEMP ?  ;                                    CR .( SHOULD PRINT 4   )  TEST2  CR                                                                                             N:  ." HELLO " ; IS TEMP                                        : TEST3  TEMP ;                                                 CR .( SHOULD SAY HELLO   ) TEST3 CR