如何在模型设置中禁用世界包装时使用原语"patch-right-ahead-ahead"？

Question

我对原语"patch-right-ahead-ahead"有疑问.在模型设置中禁用世界包装时,我收到以下错误消息:

OF expected input to be a turtle agentset or patch agentset or turtle or patch but got NOBODY instead.

当我做 :

if [pcolor] of patch-here = brown [
 if [pcolor] of (patch-right-and-ahead 90 1) = brown [
  move-to patch-right-and-ahead 90 1 ] ]

在此先感谢您的帮助.

Answer 1

当通常返回代理的原语无法找到要返回的适当代理时,它将返回nobody.在这里,没有补丁在当前代理的正前方(呃,因为角度是90,我猜对了).因此,它正在回归nobody.您需要检查以确保它nobody在使用之前没有of:

if [pcolor] of patch-here = brown [
  let target-patch patch-right-and-ahead 90 1
  if target-patch != nobody and [pcolor] of target-patch = brown [
    move-to target-patch
  ]
]