[Tutor] Input

[Tiger12506]

Try regular expressions in the re module. This should make this code below 
much much simpler. Downside is you have to learn a slightly different 
syntax. Upside is - regular expressions are very powerful.



> Last week someone had an issue with raw_input() and how to get input for
> a number. So I remembered my CP/M times and got to think of a little
> function I had there. The function is lost and my time is scarce but I
> made a little effort and here you have the results. It has loads of room
> for improvement and probably a few bugs but it's a starting point, and
> it should guarantee that you get the input you need.
> You just define your mask and the functions checks the input
> accordingly, it returns a string.
> You might improve it by displaying the mask, e.g. for mask = '9999.99'
> you might see in the screen ____.__ or for mask = '999-AAA::9999' you'd
> see ___-___::___ so the user will know the format of what's expected of
> him, also a beep on incorrect entry might prove nice.
>
> HTH
>
> -----------------------------------------------------------------------
> import msvcrt
>
> _validChars = {
>                'X' :
> 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890'
>                , '9' : '1234567890'
>                , '-' : '-1234567890'
>                , 'A' :
> 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'
>                , '!' : 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'}
> _validKeys = _validChars.keys()
>
> def maskInput(mask, separators = True) :
>    lmask = list(mask)
>    lmask.reverse()
>    usedMask = []
>    retInput = ''
>    c = ''
>    maskChar = lmask.pop()
>    try :
>        while maskChar not in _validKeys :
>            if separators :
>                retInput += maskChar
>            msvcrt.putch(maskChar)
>            maskChar = lmask.pop()
>    except IndexError : pass
>
>    c = msvcrt.getch()
>    while c != chr(13) :
>        if maskChar and maskChar not in _validKeys and c in
> _validChars[lmask[-1]] :
>            if separators :
>                retInput += maskChar
>            msvcrt.putch(maskChar)
>            usedMask.append(maskChar)
>            maskChar = lmask.pop()
>        if usedMask and c == '\b' :
>            try :
>                if maskChar :
>                    lmask.append(maskChar)
>                maskChar = usedMask.pop()
>                retInput = retInput[:-1]
>                msvcrt.putch(c)
>                msvcrt.putch(' ')
>                msvcrt.putch(c)
>                while usedMask[-1] not in _validKeys :
>                    if maskChar :
>                        lmask.append(maskChar)
>                    maskChar = usedMask.pop()
>                    if separators :
>                        retInput = retInput[:-1]
>                    msvcrt.putch(c)
>                    msvcrt.putch(' ')
>                    msvcrt.putch(c)
>            except IndexError : pass
>        elif maskChar and c in _validChars[maskChar] :
>            retInput += c
>            msvcrt.putch(c)
>            try :
>                usedMask.append(maskChar)
>                maskChar = lmask.pop()
>              #  while maskChar not in _validKeys :
>            except IndexError :
>                maskChar = ''
>        c = msvcrt.getch()
>    return retInput
>
> if __name__ == '__main__' :
>    invar = maskInput('-9999.99')
>    print
>    print invar
>
> ------------------------------------------------------------------------
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