如何捕获 TypeError 并打印自定义消息？

Question

I am trying to create a function to check if a path exists or not, but when I call my function without any parameter it does not catch typerror and throw me an error.

Code:

def checkPath(pathName):
    try:
        import os, sys
        try:
            if pathName.strip() == '' or pathName is None:
                raise TypeError("No parameter is passed to function : checkPathExist(pathName)")
            else:
                try:
                    if os.path.isdir(pathName):
                        print('Source path exist : ', pathName)
                    else:
                        raise Exception("Invalid Path Found : ", pathName)
                except Exception as error:
                    print('Error : ' + repr(error))
                    quit()
        except Exception as error:
            print('Error : ' + repr(error))
            quit()
    except TypeError:
        raise Exception("No argument passed ...")

    except Exception as error:
        print('Error : ' + repr(error))
        quit()

Following is the way I am calling my function without parameters. I want to print custom message if no parameter is passed.

checkPath()

Answer 1

If you call your function without an argument it will throw a TypeError at the call to the function not within it. So if you want to handle no arguments as a type error inside the function you should provide a default value for your argument and then raise the error if the default value is unchanged. Somthing like this:

def checkPath(mypath = ""):

  try:
    if myPath == "":
        raise TypeError
    
    import os,sys
    
    try:

      if pathName.strip() == '' or pathName is None :
        
        raise TypeError("No parameter is passed to function : checkPathExist(pathName)")
      
      else:

        try:

          if os.path.isdir(pathName):
            
            print('Source path exist : ',pathName)
          
          else:
            
            raise Exception("Invalid Path Found : ",pathName)
        
        except Exception as error:
          
          print('Error : ' + repr(error))
          quit()

    except Exception as error:
      print('Error : ' + repr(error))
      quit()

  except TypeError:
    raise Exception("No argument passed ...")

  except Exception as error:
    print('Error : ' + repr(error))
    quit()

Answer 2

change the first line of function to initialize variable mypath with some default value. Maybe None .

Try this:

def checkPath(mypath=None):

If you dont initilize the variable, you must pass a value while calling method, else it would throw error to state you cannot call the function (1 argument is needed)