在Python中重用內部函數

Question

我想弄清楚如何在多個其他函數中使用Python 3函數（使用非局部變量），而無需再次定義它。這裏是我的意思非常簡單的例子：

def inner(airplane): 
    nonlocal var 
    if airplane == "Alpha": 
     var = a 
    elif airplane == "Beta": 
     var = b 
def outer1(airplane): 
    inner(airplane) 
    do stuff with var 
def outer2(airplane) 
    inner(airplane) 
    do other stuff with var 

outer1("FirstAirplane") 
outer2("SecondAirplane") 

我得到一個錯誤（SyntaxError: No binding for nonlocal 'var' found），但我懷疑我是非常錯誤的事情了。我不打算自行運行inner()。我如何重用inner()正確的方法？我不能在outer1()裏面定義它，然後在outer2()中重新使用它，我可以嗎？

好吧，由呃......大衆的需求...這裏是我的代碼中的相關部分...

def planeandoffset(airplane): 
    if airplane == "Zulu": 
     linename = "\\[\\INOV" 
     charoffset = 14 
    elif airplane == "Lima": 
     linename = "\\[\\ILIM" 
     charoffset = 10 
    elif airplane == "Mike": 
     linename = "\\[\\IMIK" 
     charoffset = 10 
    else: 
     print("There is no airplane by that name.") 
    latstart = charoffset 
    latend = 7 + charoffset 
    lonstart = 9 + charoffset 
    lonend = 17 + charoffset 
    return airplane, linename, latstart, latend, lonstart, lonend 

def latlongen(workingline, latstart, latend, lonstart, lonend): 
# Determine Latitude and Longitude in decimal format 
    latraw = workingline[latstart:latend] 
    if latraw[0:1] == "S": 
     pm = "-" 
    else: 
     pm = "" 
    hours = float(latraw[3:5] + "." + latraw[5:]) 
    decimal = hours/60 
    latitude = float(latraw[1:3]) + decimal 
    latitude = float(pm + str(latitude)) 
    lonraw = workingline[lonstart:lonend] 
    if lonraw[0:1] == "W": 
     pm = "-" 
    else: 
     pm = "" 
    hours = float(lonraw[4:6] + "." + lonraw[6:]) 
    decimal = hours/60 
    longitude = float(lonraw[1:4]) + decimal 
    longitude = float(pm + str(longitude)) 
    return latitude, longitude 
def kmlplanegen(airplane): 
    planeandoffset(airplane) 
    global afffilename, iconurl, kmlwrite 
    affread = open(afffilename) 
    while True: 
     line = affread.readline() 
     # Choose appropriate line 
     if line.startswith(linename): 
      workingline = line 
     elif len(line) == 0: # Zero length indicates EOF (Always) 
      break 
     else: 
      pass 
    try: 
     latlongen(workingline, latstart, latend, lonstart, lonend) 
    # Generate kml for Airplane 
     print(''' <Placemark> 
      <Style> 
       <IconStyle> 
        <Icon> 
         <href>{0}</href> 
        </Icon> 
       </IconStyle> 
      </Style> 
      <name>{1}</name> 
      <description>Latitude: {2} Longitude: {3}</description> 
      <Point> 
       <coordinates>{3},{2},0</coordinates> 
      </Point> 
     </Placemark>'''.format(iconurl,airplane,latitude,longitude), file=kmlwrite) 
    except Exception: 
     exit(1, "There was an error. This message is kind of worthless. Stopping Program") 

def kmlpathgen(airplane): 
    planeandoffset(airplane) 
    global afffilename, kmlwrite 
    # Generate kml for Airplane Path 
    print(''' <Style id="yellowLineGreenPoly"> 
     <LineStyle> 
      <color>7f00ffff</color> 
      <width>4</width> 
     </LineStyle> 
     <PolyStyle> 
      <color>7f00ff00</color> 
     </PolyStyle> 
    </Style> 
    <Placemark> 
     <name>{0} Path</name> 
     <description>Transparent green wall with yellow outlines</description> 
     <styleUrl>#yellowLineGreenPoly</styleUrl> 
     <LineString> 
      <extrude>1</extrude> 
      <tessellate>1</tessellate> 
      <altitudeMode>relativeToGround</altitudeMode> 
      <coordinates>'''.format(airplane), file=kmlwrite) 
    try: 
     affread = open(afffilename) 
     while True: 
      line = affread.readline() 
      if len(line) == 0: # Zero length indicates EOF (Always) 
       break 
      elif line.startswith(linename): 
       workingline = line 
       latlongen(workingline, latstart, latend, lonstart, lonend) 
       print("     {0},{1},0".format(longitude,latitude), file=kmlwrite) 
      else: 
       pass 
    except NameError: 
     pass 
    finally: 
     print('''   </coordinates> 
      </LineString> 
     </Placemark>''', file=kmlwrite) 

Answer 1

你剛開始學習編程？

忘掉非本地任何東西。要做到這一點，正確的方法是用return var返回var，再用這個結果在調用上下文分配：

var = inner(airplane) 

編輯：

如果你簡單地調用：

planeandoffset(airplane) 

你沒有對返回的值做任何事情。要訪問它們，請執行以下操作：

airplane, linename, latstart, latend, lonstart, lonend = planeandoffset(airplane) 

我不打算分析你在用這些全局變量做什麼，但不管它是什麼，停止。可以將這些參數作爲函數之間的參數傳遞，也可以將它們與函數一起放入一個類中，然後將它們作爲類的成員進行訪問。

無論哪種方式，我建議你按照教程來學習更常用的不使用全局變量的編程風格。