Self-Referencing Customtype Library

[SMcNeill]

Just something rather neat that I thought I'd share, even if I haven't honestly sorted out an use for it (yet)...

Code: QB64: [Select]

1. DECLARE CUSTOMTYPE LIBRARY 'Use Customtype for self-referencing a sub written inside your program
2.     SUB SUB_EXAMPLE (BYVAL passed AS _OFFSET) 'this points to SUB EXAMPLE below, but uses an OFFSET to point to its parameter.
3.     'NOTE:  The sub/function name *MUST* be the same as QB64 translates it as, for us.
4.     'General rule of thumb is to make the subname ALL CAPS, preceeded by SUB_ or FUNCTION_ as dictated.
5.  
6.     SUB SUB_EXAMPLE2 (BYVAL passed AS _OFFSET)
7. END DECLARE
8.  
9. TYPE DataType 'A datatype to use as an example
10.     x AS STRING * 12
11.     y AS LONG
12.     z AS LONG
13. END TYPE
14.  
15. TYPE DataType2 'a second datatype
16.     byte1 AS _UNSIGNED _BYTE
17.     byte2 AS _UNSIGNED _BYTE
18.     byte3 AS _UNSIGNED _BYTE
19.     byte4 AS _UNSIGNED _BYTE
20.     byte5 AS _UNSIGNED _BYTE
21.     byte6 AS _UNSIGNED _BYTE
22.     byte7 AS _UNSIGNED _BYTE
23.     byte8 AS _UNSIGNED _BYTE
24.     byte9 AS _UNSIGNED _BYTE
25.     byte10 AS _UNSIGNED _BYTE
26.     byte11 AS _UNSIGNED _BYTE
27.     byte12 AS _UNSIGNED _BYTE
28.     byte13 AS _UNSIGNED _BYTE
29.     byte14 AS _UNSIGNED _BYTE
30.     byte15 AS _UNSIGNED _BYTE
31.     byte16 AS _UNSIGNED _BYTE
32.     byte17 AS _UNSIGNED _BYTE
33.     byte18 AS _UNSIGNED _BYTE
34.     byte19 AS _UNSIGNED _BYTE
35.     byte20 AS _UNSIGNED _BYTE
36. END TYPE
37.  
38.  
39.  
40. DIM m AS _MEM 'A memblock to store some information
41. m = _MEMNEW(20) 'The proper size to fill the data type that we're interested in passing back to our program.
42. _MEMPUT m, m.OFFSET, "Hello World" '12 bytes
43. _MEMPUT m, m.OFFSET + 12, -2 AS LONG '4 more
44. _MEMPUT m, m.OFFSET + 16, 3 AS LONG '4 more to make all 20
45.  
46. SUB_EXAMPLE m.OFFSET 'Call the sub with the offset to these 20 bytes of memory
47. SLEEP
48. SUB_EXAMPLE2 m.OFFSET 'Notice, we passed the same block of memory, but are handling it differently here,
49. '                            according to the paramters set in the second sub
50.  
51. _MEMFREE m
52.  
53.  
54.  
55. END
56.  
57. SUB Example (t AS DataType) 'And here, we want to set up the actual sub to work with our example datatype.
58.     PRINT t.x 'print the values of that memblock
59.     PRINT t.y
60.     PRINT t.z
61. END SUB
62.  
63. SUB Example2 (x AS DataType2)
64.     COLOR 12
65.     PRINT x.byte1
66.     PRINT x.byte2
67.     PRINT x.byte3
68.     PRINT x.byte4
69.     PRINT x.byte5
70.     PRINT x.byte6
71.     PRINT x.byte7
72.     PRINT x.byte8
73.     PRINT x.byte9
74.     PRINT x.byte10
75.     PRINT x.byte11
76.     PRINT x.byte12
77.     PRINT x.byte13
78.     PRINT x.byte14
79.     PRINT x.byte15
80.     PRINT x.byte16
81.     PRINT x.byte17
82.     PRINT x.byte18
83.     PRINT x.byte19
84.     PRINT x.byte20
85. END SUB