使用分形，類和swampy製作二叉樹TurtleWorld - Python - 調試

Question

我有這段代碼，它讀取並解析分形描述語言文件，然後使用FractalWorld，這是TurtleWorld的特殊版本，它只是去除烏龜，並沒有延遲。

import math, random, sys 
from FractalWorld import * 

world = FractalWorld(width=1000,height=1000,delay=0) 
Rasmus = Fractal(draw=False) 

class command(object): 
    def __init__(self, cmd, l): 
      self.cmd = cmd 
      self.l = l 

    def execute(self, turtle, length): 
      if self.cmd=='lt': 
        lt(turtle, int(self.l[0])) 
      if self.cmd=='rt': 
        rt(turtle, int(self.l[0])) 
      if self.cmd=='fd': 
        fd(turtle, length) 
      if self.cmd=='bk': 
        bk(turtle, length) 
      if self.cmd=='scale': 
        lenght = length*float(self.l[0]) 

class rule(object): 
    def __init__(self): 
      self.rule={} #we make an empty dictionary 

    def newrule(self,leftside,rightside): 
      self.rule[leftside]=rightside #we fill the dictionary 

    def expand (self,oldlist,depth): 
      if depth <= 0: 
        return oldlist 
      newlist=[] # we make an empty new list 
      for i in oldlist: 
        if i not in self.rule: 
          newlist.append(i) 
        else: 
          newlist.append(self.expand(self.rule[i],depth-1)) 
      return newlist 

class Fractal(object): 
    def __init__(self, start, rules, commands, length, depth): 
      self.start = start 
      self.rules = rules 
      self.commands = commands 
      self.length = length 
      self.depth = depth 

    def draw(self, oldlist): 
      for i in oldlist: 
        if type(i) == list: 
          self.draw(i) 
        else: 
          cmd = self.commands[i] 
          cmd.execute(Rasmus, self.length) 

def read(): 
    files = open('tree.fdl') 
    commands = {} 
    r = rule() 
    for line in files: 
      line = line.strip() 
      oldlist = line.split(' ') 
      if oldlist[0] == 'start': 
        start = oldlist[1:] 
      elif oldlist[0] == 'rule': 
        r.newrule(oldlist[1], oldlist[3:]) 
      elif oldlist[0] == 'cmd': 
        cmd = command(oldlist[2], oldlist[3:]) 
        commands[oldlist[1]] = cmd 
      elif oldlist[0] == 'length': 
        length = int(oldlist[1]) 
      elif oldlist[0] == 'depth': 
        depth = int(oldlist[1]) 
    return Fractal(start, r, commands, length, depth) 

re = read() 

print re.commands.keys() 

l = re.rules.expand(re.start , re.depth) 
re.draw(l) 


wait_for_user() 

的FDL文件將作出二叉樹，它看起來像這樣：

start X 

rule X -> F L D X R X U L B 

length 100 

depth 10 

cmd X nop 

cmd F fd 

cmd B bk 

cmd R rt 70 

cmd L lt 35 

cmd D scale 0.7 

cmd U scale 1.4285714285714286 

我的問題是有一個bug，在我的翻譯。看起來解釋器沒有正確讀取比例尺，而是按比例縮放我的線條作爲樹枝的下一個深度。我試圖調試它，但一直沒能做到。

Answer 1

lenght = length*float(self.l[0]) 

此行有兩個錯誤。首先，一個錯字。但是，即使這個名字是正確的，你也可以將一個新值賦給一個局部變量，作爲你在函數中做的最後一件事，這是毫無意義的。您可能應該用xxx.length替換它，以便調用該函數可以更改其值。我寫爲xxx的對象可能是調用者可用的分形實例;那麼你會將它作爲參數傳遞，而不是length。