# Implicit Control Flow Implicit control flow is an optional modification to the way ChoiceScript behaves. It changes ChoiceScript's requirements by removing the need for `*finish`, `*goto`, `*goto_scene`, or `*ending` at the end of `*choice`, `*elseif`, and `*else`.\ 隐式控制流是对 ChoiceScript 行为方式的一种可选修改。它改变了 ChoiceScript 的要求，移除了在 `*choice`、`*elseif` 和 `*else` 末尾需要使用 `*finish`、`*goto`、`*goto_scene` 或 `*ending` 的必要性。 Devblog update: \ 开发博客更新： ## Usage 用法 To use implicit control flow, simply add the following to your `*create` variable section in startup.txt:\ 要使用隐式控制流，只需在startup.txt文件的`*create`变量部分添加以下内容： ```choicescript *create implicit_control_flow true ``` (You can also `*set implicit_control_flow true` or `false` in other places in your scene files.)\ （您也可以在场景文件的其他位置`*set implicit_control_flow`为`true`或`false`。） ## Features 特性 Usually, in ChoiceScript, the code below would produce an error:\ 通常，在ChoiceScript中，以下代码会产生错误： ```choicescript *temp player_gender "Male" Coming inside, your friend greets you. *if (player_gender = "Female") "Hey girl!" *elseif (player_gender = "Nonbinary") "Hey pal!" *else "Hey man!" Still smilling, your friend continues, "How're you today?" ``` The error produced here would be:\ 此处产生的错误为： > "It is illegal to fall in to an `*else` statement; you must `*goto` or `*finish` before the end of the indented block." As seen in the previous `*choice`, `*elseif`, and `*else` pages, ChoiceScript requires that all of these commands have either a `*finish`, `*goto`, `*goto_scene`, or `*ending` at the end of the code block; otherwise, the code will throw up an error.\ 如先前 `*choice`、`*elseif` 和 `*else` 页面所述，ChoiceScript要求所有这些命令在代码块末尾必须包含 `*finish`、`*goto`、`*goto_scene` 或 `*ending`；否则，代码将抛出错误。 So to correct that, the following changes would be needed:\ 因此，要修正这一点，需要进行以下更改： ```choicescript *temp player_gender "Male" Coming inside, your friend greets you. *if (player_gender = "Female") "Hey girl!" *goto smilling_friend *elseif (player_gender = "Nonbinary") "Hey pal!" *goto smilling_friend *else "Hey man!" *goto smilling_friend *label smilling_friend Still smilling, your friend continues, "How're you today?" ``` As seen here, if you want to simply proceed down the file, the use of several `*gotos` is quite redundant. Games that feature heavy use of `*if`, `*elseif`, and `*else` might end up with dozens or more of these extra `*gotos` and `*labels` just to proceed through simple `*if/*elseif/*else` sequences.\ 正如这里所见，如果你只想简单地按顺序执行文件中的代码，使用多个 `*goto` 语句就显得相当冗余。那些大量使用 `*if`、`*elseif` 和 `*else` 语句的游戏，可能最终会为了处理简单的 `*if/*elseif/*else` 序列而添加数十个甚至更多的额外 `*goto` 和 `*label` 语句。 By using implicit control flow, however, the requirement for `*gotos` and `*labels` is removed. Our very first code example would not flag any errors and would proceed down the code without requiring the extra `*gotos` and `*labels`.\ 然而，通过使用隐式控制流，就无需 `*goto` 和 `*label` 语句了。我们最初的代码示例将不会标记任何错误，并且可以在不需要额外 `*goto` 和 `*label` 语句的情况下顺序执行代码。 When implicit control flow is enabled, `*choice` works basically the same as `*fake_choice`, except you can also freely nest a `*choice` inside another `*choice` with implicit control flow.\ 启用隐式控制流时，`*choice` 的功能基本与 `*fake_choice` 相同，区别在于你还可以在隐式控制流中，自由地将一个 `*choice` 嵌套在另一个 `*choice` 内部。 ## Notes 注意事项 Implicit control flow is convenient, but ChoiceScript's original behavior can help find unintended bugs.\ 隐式控制流虽然方便，但 ChoiceScript 的原始行为有助于发现意外的程序错误。 ```choicescript *choice #Be very naughty. Santa refuses to give you a present. #Be mostly nice. Santa gives you a present reluctantly. #Be as nice as can be. Santa gives you a present enthusiastically. Inside the gift box is a video game! ``` In the following example, the `*choice` will behave as a `*fake_choice`; all options will proceed down the code. If choice `#1` is selected, it will mention that Santa refused to give you a present—but because the code continues down, you will still receive the video game.\ 在以下示例中，`*choice` 将表现得像 `*fake_choice`；所有选项都会继续执行后续代码。如果选择了选项 `#1`，它会提到圣诞老人拒绝给你礼物——但由于代码继续向下执行，你仍然会收到视频游戏。 Therefore, if the author forgets to include a different branch for choice `#1`, the previous error message could remind them to check their branching.\ 因此，如果作者忘记为选项 `#1` 设计不同的分支，之前的错误提示可以提醒他们检查分支逻辑。 Another advantage of implicit control flow is that branches are immediately apparent because of using `*goto`; any `#options` that do not branch will not have a `*goto` following.\ 隐式控制流的另一个优势在于，由于使用了 `*goto` 指令，分支结构一目了然；任何未设置分支的 `#options` 都不会跟随 `*goto` 指令。 To use the Santa example, with original CS, you would need:\ 以圣诞老人为例，在原始ChoiceScript中，你需要编写： ```choicescript *choice #Be very naughty. Santa refuses to give you a present. *goto coal #Be mostly nice. Santa gives you a present reluctantly. *goto present #Be as nice as can be. Santa gives you a present enthusiastically. *goto present *label present Inside the gift box is a video game! *finish *label coal You get a lump of coal instead. *finish ``` With implicit control flow, the same passage could read:\ 通过隐式控制流，同一段文字可以这样表达： ```choicescript *choice #Be very naughty. Santa refuses to give you a present. *goto coal #Be mostly nice. Santa gives you a present reluctantly. #Be as nice as can be. Santa gives you a present enthusiastically. Inside the gift box is a video game! *finish *label coal You get a lump of coal instead. *finish ``` It's immediately visible that `#option A` branches, but `#B` and `#C` fall directly through.\ 可以立即看出，`#选项A` 会分支，但 `#B` 和 `#C` 会直接顺序执行。 ## Known Bug 已知错误 While implicit control flow seems like a powerful tool, there's a specific scenario where it doesn't function well.\ 虽然隐式控制流看起来是一个强大的工具，但在某些特定场景下它并不能很好地发挥作用。 ```choicescript *label haha *choice #varA *set varB true text *if varB #varB text *finish *goto haha ``` The expected interpretation of that code would be the player is given an only choice `#varA` upon the first visit of "haha". Picking `#varA` would loop the player back to the beginning of "haha," but now they can pick either `#varA` again or the now-revealed `#varB`.\ 这段代码的预期解释是，玩家在首次访问"haha"时仅获得选项 `#varA`。选择 `#varA` 会使玩家循环回到"haha"的开头，但此时他们可以再次选择 `#varA`，或选择现已显示的 `#varB`。 However, CS throws an error when the player picks `#varA`: "It is illegal to fall out of a `*choice` statement; you must `*goto` or `*finish` before the end of the indented block." Removing the command `*set varB true`, however, fixes the error, although the player will now be trapped in an infinite limbo of `#varA`. A simple fix would be moving the `*goto hehe` inside the body of `#varA`, though this begs up the question, "why bother using implicit control flow at all?"\ 然而，当玩家选择 `#varA` 时，CS 会抛出一个错误："从 `*choice` 语句中跳出是非法的；在缩进块结束前必须使用 `*goto` 或 `*finish`。"不过，移除命令 `*set varB true` 可以修复此错误，尽管玩家现在将陷入 `#varA` 的无限循环困境。一个简单的解决方法是将 `*goto hehe` 移到 `#varA` 的代码块内部，但这引出了一个问题："何必费心使用隐式控制流呢？" ## Comparison 比较 Here is a simple visual comparison with ICF on and off:\ 以下是开启与关闭隐式控制流的简单视觉对比： --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://raster.gitbook.io/zh-hans_choicescript-guide/implicit-control-flow.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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