HCoop / bpt / guile.git / blame
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1 | -*- outline -*- |
| 2 | ||
| 3 | * Overview | |
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4 | |
| 5 | This directory includes an example program for extending Guile with a | |
| 6 | new (and even useful) data type. | |
| 7 | ||
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8 | |
| 9 | * Build Instructions | |
| 10 | ||
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11 | To build the example, simply type |
| 12 | ||
| 13 | make box | |
| 14 | ||
| 15 | in this directory. | |
| 16 | ||
| 17 | The resulting `box' program is a Guile interpreter which has one | |
| 18 | additional data type called `box'. | |
| 19 | ||
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20 | |
| 21 | * The Box Data Type | |
| 22 | ||
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23 | A box is simply an object for storing one other object in. It can be |
| 24 | used for passing parameters by reference, for example. You simply | |
| 25 | store an object into a box, pass it to another procedure which can | |
| 26 | store a new object into it and thus return a value via the box. | |
| 27 | ||
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28 | |
| 29 | ** Usage | |
| 30 | ||
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31 | Box objects are created with `make-box', set with `box-set!' and |
| 32 | examined with `box-ref'. See the following example session for usage | |
| 33 | details: | |
| 34 | ||
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35 | |
| 36 | ** Example Session | |
| 37 | ||
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38 | $ ./box |
| 39 | guile> (define b (make-box)) | |
| 40 | guile> b | |
| 41 | #<box #f> | |
| 42 | guile> (box-set! b '(list of values)) | |
| 43 | guile> b | |
| 44 | #<box (list of values)> | |
| 45 | guile> (box-ref b) | |
| 46 | (list of values) | |
| 47 | guile> (quit) | |
| 48 | $ |