<p>它使用<code>validatecommand</code>将<code>tk.Entry</code>中的有效用户输入限制为可以解释为浮点的字符串:</p>
<pre><code>import tkinter as tk
class window2:
def __init__(self, master1):
self.panel2 = tk.Frame(master1)
self.panel2.grid()
self.button2 = tk.Button(self.panel2, text = "Quit", command = self.panel2.quit)
self.button2.grid()
vcmd = (master1.register(self.validate),
'%d', '%i', '%P', '%s', '%S', '%v', '%V', '%W')
self.text1 = tk.Entry(self.panel2, validate = 'key', validatecommand = vcmd)
self.text1.grid()
self.text1.focus()
def validate(self, action, index, value_if_allowed,
prior_value, text, validation_type, trigger_type, widget_name):
if value_if_allowed:
try:
float(value_if_allowed)
return True
except ValueError:
return False
else:
return False
root1 = tk.Tk()
window2(root1)
root1.mainloop()
</code></pre>
<p>参考文献:</p>
<ul>
<li><a href="http://www.tcl.tk/man/tcl8.5/TkCmd/entry.htm#M-validate" rel="nofollow noreferrer">Tk man page</a>解释了<code>validate</code>和<code>validatecommand</code>
选项。(感谢<a href="https://stackoverflow.com/users/60725/schlenk">schlenk</a>的链接)。</li>
<li>我在Python中学会了如何做到这一点。</li>
</ul>