具有十六进制值的Python ttk条目验证

Question

I've been thinking in a way to validate a ttk Entry box for a Hex value of 4 characters.

I came to a solution but I'm not sure if there is a more correct/pythonist way to do it.

This is the Entry declaration:

vcdmCheckSum = (self.register(self.OnValidateCheckSum), '%P', '%d')
self.tlCheckSumEntry = Entry(self, validate="key", validatecommand=vcdmCheckSum, width=10)                
self.tlCheckSumEntry.grid(row=self.rowOptions2, column=self.columnOptions1, sticky=tk.W+tk.N, padx=5, pady=5)

And this is my OnValidateCheckSum function:

def OnValidateCheckSum(self, P, d):
    # If you are not writting but deleting
    if d <> '1':
        return True
    try:            
        return (len(P) < 5) and (int(P, 16) <= int('FFFF', 16))
    except:
        return False

The tricky thing is that if I use int(P, 16) without checking the max value and start writing a 0 It wont work since int('0') is false as int('0', 16).

So, once again. Is that the way to do it? Is there a better or more "pythonic" way to do so?

Answer 1

Assuming there are no special characters in the string (like $ or 0x):

def OnValidateCheckSum(self, P, d):
    valid_hex_char = lambda c: c in 'abcdef0123456789'
    return (len(P) < 5) and (all(valid_hex_char(z) for z in P.lower()))