Re: How to check whether a character (or one-character string) is a letter?

[Marcin Borkowski <mbork@wmi.amu.edu.pl>]

On 2014-10-04, at 06:08, Yuri Khan wrote:

> On Sat, Oct 4, 2014 at 7:29 AM, Marcin Borkowski <mbork@wmi.amu.edu.pl> wrote:
>
>> The reason I'm asking is that I'm writing a function which converts an
>> arbitrary string to a valid (and nice) filename (e.g., only letters and
>> hyphens) - so basically I want to walk a string character by character
>> and convert any space to a hyphen and omit any other non-letter.  Am I
>> reinventing the wheel?
>
> What are your assumptions about input string arbitrariness, your
> requirements about output filename niceness, and your requirements
> about the properties of the mapping?
>
> Because these may be in conflict.
>
> For example, if you assume any arbitrary strings, want only
> [-0-9A-Za-z_] characters, and want reasonably different strings to map
> into different filenames, then you will end up having to preserve
> non-nice characters as ugly character encodings (in the spirit of
> urlencode, XML character references, or Punycode). Otherwise, whole
> words or sentences in Russian, Japanese or Greek will map into an
> empty filename.

Good point.  However, I intend to keep a list of filenames, and in case
some of them is already taken, append a number to it.  (This is an
extremely primitive hashing function, but it will suffice for my needs.)

Regards,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Adam Mickiewicz University