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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Sat, 9 Aug 2014 01:57:18 -0600
Subject: Re: Template language for random string generation
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Xref: csiph.com comp.lang.python:75936

On Sat, Aug 9, 2014 at 1:49 AM, Ian Kelly <ian.g.kelly@gmail.com> wrote:
> On Sat, Aug 9, 2014 at 12:52 AM, Paul Wolf <paulwolf333@gmail.com> wrote:
>> On Friday, 8 August 2014 23:03:18 UTC+1, Ian  wrote:
>>> Have you given any thought to adding a validation mode, where the user
>>> provides a template and a string and wants to know if the string
>>> matches the template?
>>
>> Isn't that what regular expressions are? Or do you have a clarifying use case?
>>
>> strgen is provided as the converse of regular expressions.
>
> The syntax is not equivalent though. You can't take a strgen template,
> pass it into the re module, and just expect it to work.
>
> Also, I'm not sure how best to go about writing a regular expression
> for, e.g. "12 or more letters, digits, and punctuation, including at
> least one each of uppercase letter, lowercase letter, digit, and
> punctuation". I'm fairly certain that language is regular, but
> actually matching it with a regular expression would be a nightmare.

To clarify further, validating that *without* using a regular
expression is not too terribly difficult, but the value that I see in
validating it with a strgen is that one could then be sure that one's
string generation and validation were equivalent. In contrast, if you
have a strgen for generation and a series of string manipulations for
validation, then it's hard to be certain there aren't any differences.