试图欺骗NetLogo执行作为参数传递的函数 [英] Attempting to trick NetLogo into executing a function passed as an argument

问题描述

以下内容会产生编译错误.

The following produces a compilation error.

to-report call-first/last [first/last a-list]
  report first/last a-list
end

正文中的

a-list 突出显示，并显示错误: Expected command.

a-list in the body is highlighted with the error: Expected command.

所以我尝试了以下方法.

So I tried the following.

to-report call-first/last [first/last a-list]
  report first map first/last (list a-list)
end

此代码已编译(！)，但是当我尝试让观察者执行它时

This code compiled(!), but when I attempted to have the observer execute it

call-first/last first [1 2 3]

呼叫优先/最后突出显示，并显示错误消息: CALL-FIRST/LAST预期有2个输入.

call-first/last was highlighted with the error message: CALL-FIRST/LAST expected 2 inputs.

对替代方法有何想法?

谢谢.

P.S.更大的前景是找到一种方法(如果有的话)在NetLogo中编写一个高阶函数.

P.S. The bigger picture is to find a way (if there is one) to write a higher-order function in NetLogo.

更新:

要求观察者正确执行以下工作！

Asking the observer to execute the following works properly!

通话优先[[a-list]->第一个a-list] [1 2 3] ;;=>1

call-first-last [[a-list] -> first a-list] [1 2 3] ;; => 1

通话优先[[a-list]->最后一个列表] [1 2 3] ;;=>3

call-first-last [[a-list] -> last a-list] [1 2 3] ;; => 3

但是肯定还有很长的路要走！

But it sure is a long way around!

另一个更新:

尝试

to-report call-first-last [first-last a-list]
  report first map (runresult first-last) (list a-list)
end

已编译.

但是要求观察者运行 call-first-last"first"命令.[1 2 3] 产生了运行时错误:首先需要1个输入

But asking the observer to run call-first-last "first" [1 2 3] produced a Runtime Error: FIRST expected 1 input

所以问题似乎归结为是否存在一种方法(除了使用上述匿名表达式之外)来编写返回函数的表达式?

So the question seems to come down to whether there is a way (other than using an anonymous expression as above) to write an expression that returns a function?

推荐答案

我不确定所有细节是否正确，但是当我看到您要执行的操作时，我的第一个想法就是使用 runresult .这有效:

I'm not sure I have all the details correct, but my first thought when I saw what you were trying to do is to use runresult. This works:

to-report call-first-last [first-last a-list]
  report runresult word first-last a-list
end

使用(例如):call-first-last"last"[1 2 3]

With (for example): call-first-last "last" [1 2 3]

当您使用两个以上的术语来编写更复杂的表达式时，您将需要为 word 和 runresult 添加一些括号.

You would need to add some brackets for both word and runresult as you do more complicated expressions with more than two terms.

这篇关于试图欺骗NetLogo执行作为参数传递的函数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！