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92 lines
2.8 KiB
Markdown
92 lines
2.8 KiB
Markdown
# 9.练习：生成代码
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*到目前为止，我们的冒险游戏有 10 个对象。每个对象由有 5 个属性组成。一个真正的文本冒险可能有数百个甚至数千个对象，并且每个对象的属性数量也可能增加（请参阅下一章）。在目前的形式下，维护如此庞大的对象和属性列表将很困难。*
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例如，当我们在添加对象 *wallField* 和 *wallCave* 时，我们必须在三个不同的位置执行此操作：一次在 *object.h* 中（作为<em>#define</em>），两次在 *object.c* 中（数组 *objs* 中的一个元素，以及一个单独的标签数组）。这显然十分笨拙并且容易出错。
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我们将不再手工维护 object. h 和 object. c，而是从更适合我们需要的单一源开始生成文件。这个新的源文件可以用你喜欢的任何语言 ( 典型的是某些特定领域的语言 )，只要你有工具把它转换回 C。下面是一个简单的例子，考虑下列布局来组织我们的对象：
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```txt
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/* Raw C code (declarations) */
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- ObjectName
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AttributeName AttributeValue
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AttributeName AttributeValue
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...
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- ObjectName
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AttributeName AttributeValue
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AttributeName AttributeValue
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...
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- ...
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```
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根据到目前为止收集的对象，我们可以构造以下源文件。文件名并不重要;我只是简单地将其命名为*object.txt*，以明确它与*object.h*和*object.c*相关。
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## object.txt
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```txt
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#include <stdio.h>
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#include "object.h"
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typedef struct object {
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const char *description;
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const char **tags;
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struct object *location;
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struct object *destination;
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} OBJECT;
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extern OBJECT objs[];
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//对象
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- field
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description "an open field"
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tags "field"
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- cave
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description "a little cave"
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tags "cave"
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- silver
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description "a silver coin"
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tags "silver", "coin", "silver coin"
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location field
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- gold
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description "a gold coin"
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tags "gold", "coin", "gold coin"
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location cave
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- guard
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description "a burly guard"
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tags "guard", "burly guard"
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location field
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- player
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description "yourself"
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tags "yourself"
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location field
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- intoCave
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description "a cave entrance to the east"
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tags "east", "entrance"
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location field
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destination cave
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- exitCave
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description "an exit to the west"
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tags "west", "exit"
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location cave
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destination field
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- wallField
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description "dense forest all around"
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tags "west", "north", "south", "forest"
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location field
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- wallCave
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description "solid rock all around"
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tags "east", "north", "south", "rock"
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location cave
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```
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::: warning 🤔 思考题：你能否自己用 C 来实现这段伪代码？
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:::
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