Python MVC架构温度转换:为什么我得到" NameError:全局名称' view'没有定义"

时间:2014-08-13 00:45:18

标签: python global-variables nameerror self-reference

这不是一个棘手的问题,但在处理MVC架构(在VIEW,MODEL和CONTROLLER之间传递参数)时,我无法解决这个问题。

有问题:

  

Tkinter回调中的异常回溯(最近一次调用最后一次):
  文件" C:\ Python33 \ lib \ tkinter__init __。py",第1482行,调用       return self.func(* args)File" C:\ Users \ Mike \ Desktop \ code \ Assignment 6 \ glue.py",第37行,in   buttonPressed       self.model.convertTempF2C(view.fahrenheitEntrySpace.get)NameError:全局名称' view'未定义

VIEW(myFrame.py)

"""writing event handlers"""

import tkinter
import glue
class MyFrame(tkinter.Frame): #creates window for controls in an object made
                              #from a class called "tkinter.Frame" 
    """
    Class myFrame is a tkinter.Frame...
    It contains two buttons, two entry areas, and four labels:
    one button a converter;
    one button quits the program;
    one entry is for celsius;
    one entry is for fahrenheit;
    and the labels prompt user for input, and label the entry values as needed.
    """

    def __init__(self, controller):
        """
        places the controls on the frame
        """
        tkinter.Frame.__init__(self) #initilizes the superclass 
        self.pack()  #required for the buttons to show up properly.
        self.controller = controller #saves ref to controller to call methods on
                                          #contoller object when user generates events

#Fahrenheit Input Prompt
        self.fahrenheitLabel = tkinter.Label(self)
        self.fahrenheitLabel["text"] = ("Enter Fahrenheit Value:")
        self.fahrenheitLabel.pack({"side":"left"})

#Fahrenheit Entry Space
        self.fahrenheitEntrySpace = tkinter.Entry(self)
        self.fahrenheitEntrySpace == self.fahrenheitEntrySpace.insert(1, "0")  #creates starting value of 0
        self.fahrenheitEntrySpace.pack({"side":"left"})

#Fahrenheit Value label (double checked)
        self.fahrenheitLabel = tkinter.Label(self)
        self.fahrenheitLabel["text"] = ("Fahrenheit Degrees")
        self.fahrenheitLabel.pack({"side":"left"})

#Converter button (double checked)
        self.convertButton=tkinter.Button(self)
        self.convertButton["text"]= "Convert"
        self.convertButton["command"]=self.controller.buttonPressed
        # an object that remembers both self and reply when later called
        self.convertButton.pack({"side":"left"})       

#Quit button
        self.quitButton = tkinter.Button(self)
        self.quitButton["text"] = "Press\nhere to\n***QUIT***"
        self.quitButton["command"] = self.quit
        #the statement above attaches the event handler
        #self.quit() to the quit button
        self.quitButton.pack({"side":"right"})

#Celsius Value label
        self.celsiusLabel = tkinter.Label(self)
        self.celsiusLabel["text"] = ("Celsius Degrees")
        self.celsiusLabel.pack({"side":"right"})

#Celsius Entry Space
        self.celsiusEntrySpace = tkinter.Entry(self)
        self.celsiusEntrySpace["text"] == self.celsiusEntrySpace.insert(1, "0") #creates starting value of 0
        self.celsiusEntrySpace.pack({"side":"right"})


#Celsius Input Prompt
        self.celsiusLabel = tkinter.Label(self)
        self.celsiusLabel["text"] = ("Enter Celsius Value:")
        self.celsiusLabel.pack({"side":"right"})

#Test program
if __name__=="__main__":
    root = tkinter.Tk()
    view = MyFrame() #puts the frame onto the user's screen.
    view.mainloop()
    root.destroy()

MODEL(counter.py)

import tkinter
import glue

class Convert: #the MODEL

    '''
    class counter is the MODEL for a simple program that exemplifies
    the MODEL/VIEW/CONTROLLER achitecture.

    It mostly just maintains two formulas that convert Fahrenheit to Celsius
    and Celsius to Fahrenheit each time the f2C() or c2F methods are called.

    in a real MVC app, the MODEL would contain all the business logic.
    Note that the model never contains a reference to the VIEW.
    '''
    def __init__(self):
        self.fahrenheitEntrySpace = 0
        self.celsiusEntrySpace = 0

    def convertTempF2C(self):
        fahrenheit = controller.fahrenheitEntrySpace
        if fahrenheit != 0.0:
            controller.celsius = (fahrenheit - 32) * 5 / 9
        else:
            contoller.celsius = -17.7777778 

    def convertTempC2F(self):
        celsius = celsiusEntrySpace.get()
        if celsius != 0.0:
            controller.fahrenheit = (celsius *  9.0/5.0 + 32)          
        else:
            controller.fahrenheit = 32

    def __str__(self):
        return str(self.counter)

控制器(glue.py)

#Event Handler for a button in tkinter is self.yourButton["Command"] = self.yourObject.yourObjectMethod()


import tkinter
import myFrame #the VIEW
import counter #the MODEL

class Controller():

    """
    The CONTROLLER for an app that follows the MODEL/VIEW/CONTROLLER architecture.
    When the user presses a button on the VIEW,
    this controller calls the appropriate methods in the model.
    The controller handles all the communication between the model and the view.
    """

    def __init__(self):

        """
        This starts the TK framework up;
        instantiates the model;
        instantiates the VIEW;
        and states the event loop that waits for the user to press a button on the view
        """
        root = tkinter.Tk() #This starts the TK framework up;
        self.model = counter.Convert() #instantiates the model
        self.view = myFrame.MyFrame(self) #instantiates the VIEW
        self.view.mainloop() # states event loop waits for user to press button on view
        root.destroy() #lets user quit

    def buttonPressed(self):

        """
        Convert F --> C
        """

        self.model.convertTempF2C(view.fahrenheitEntrySpace.get)
        #MODEL creates new celsius temp from(fahrenheit input) 

        self.view.celsiusEntrySpace.pop()
        #replaces VIEW's old default celsius value

        self.view.celsiusEntrySpace.insert(self.model.celsius)
        #and insert's MODEL's newly converted (celsius) value

        """
        Convert C --> F
        """

        self.model.convertTempC2F(self.celsiusEntrySpace.get)
        #MODEL creates new fahrenheit temp from  (celsius input)

        self.view.fahrenheitEntrySpace.pop() 
        #replaces VIEW's old default 0 fahrenheit value 

        self.view.fahrenheitEntrySpace.insert(self.model.fahrenheit)
        #and insert's MODEL's newly converted (fahrenheit) value

if __name__=="__main__":
    c = Controller()

继续: Python Temperature conversion MVC style: why am I getting "TypeError: buttonPressed() missing 1 required positional argument: 'self'"

1 个答案:

答案 0 :(得分:0)

我认为NamerError因为错误的文件夹结构而发生。 你应该有例如

app/
|__init__.py
|counter.py
|myFrame.py

然后将所有glue.py代码放到__init__.py,但更改counter.pymyFrame.py的导入。将导入移至__init__.py的结尾

from app import myFrame
from app import counter