python中tkinter库中button如何通过command获取该button的名称

import tkinter
import webbrowser
def open_url(url):
    webbrowser.open(names['new_url%s' % t], new=0)
for t in range(0,5):
    names['new_url%s' % t]='http://www.cncotton.com/sy_59/gjmh_1401'
    names['x%s' % t] =tkinter.Button(root, text =new_d,relief="flat",command=lambda:open_url(names['new_url%s' % t]))
    names['x%s' % t].pack()
root.mainloop()

通过动态命名了5个button，然后，通过点击每个button，再进入相应的网页；但是，每次点击只会进入t=4时候的网页；我想到的解决办法是，command=函数，这个函数可以获取目前button的名称，然后通过名称再去匹配相应的url，不过如何才能获取到此时的button的名称呢

在生成Button的时候传不同参数去函数
例如

self.button1 = Tkinter.Button(self, ..., command=lambda: self.OnButtonClick(1))
...
self.button2 = Tkinter.Button(self, ..., command=lambda: self.OnButtonClick(2))

函数

def OnButtonClick(self, button_id):
    if button_id == 1:
        # self.button1 was clicked; do something
    elif button_id == 2:
        # self.button2 was clicked; do something

给Button绑定事件

from Tkinter import *

def OnButtonClick(event):
    w = event.widget                      
    print w._name

root = Tk()

but_strings = ['But1', 'But2', 'But3']  
buttons = [] 
for label in but_strings:
    button_n = Button(root, text=label)
    button_n.pack()
    button_n.bind('<Button-1>', OnButtonClick)     # 绑定事件

    buttons.append(button_n)

root.mainloop() 

names['x%s' % t] =tkinter.Button(root, text =new_d,relief="flat",command=btn_click(names['x%s' % t]))


def btn_click(b):
    open_url(b)