Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.javascript > #20322

Re: Identifying a regex

Show all headers | View raw

On 2013-06-17 04:30, Michael Haufe (TNO) wrote:
> On Jun 16, 6:47 pm, Stefan Weiss <krewech...@gmail.com> wrote:
>> What do you think is the best way to identify a value as a regular
>> expression (reference to a RegExp object)? [...]
...
> Assuming you want to avoid a combination of the above techniques,
> regular expressions also have a 'source' property that cannot be
> changed directly. So...

I'm not sure if a combination of techniques would help. Wouldn't both
the false positives and false negatives just add up?

> function isRe(re){
>     var s = re.source
>     re.source = s + "foo"
>     var p = (s == re.source)
>     if(!p) re.source = s //restore just in case
>     return p
> }

That's duck typing (of a sort), but more invasive than usual. For
example, when you call this function with a plain empty object ({}), it
will have a "source" property afterwards. It's also not safe to assume
that changing a property to a new value and then changing it back will
restore the object to its original state. And lastly, there are valid
reasons to create other (non-regex) objects with an immutable "source"
property.


- stefan

Back to comp.lang.javascript | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-17 01:47 +0200
  Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-16 19:30 -0700
    Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-17 14:05 +0200
      Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-17 16:16 -0700
        Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-18 02:13 +0200
          Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-18 20:14 +0200
            Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-18 21:39 +0200
              Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-18 23:58 +0200
                Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-25 22:05 +0200
                Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-25 16:59 -0700
                Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-26 23:47 +0200
              Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-23 20:01 +0200
        Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-18 00:40 -0700
          Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-18 10:39 +0200
            Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-18 19:32 -0700
              Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-19 14:05 +0200
                Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-19 20:24 -0700
                Re: Identifying a regex Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-20 12:27 +0200
                Re: Identifying a regex "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2013-06-20 18:08 -0700
  Re: Identifying a regex JJ <duh@nah.meh> - 2013-06-17 13:58 +0700
    Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-17 14:11 +0200
      Re: Identifying a regex JJ <duh@nah.meh> - 2013-06-18 12:46 +0700
        Re: Identifying a regex Stefan Weiss <krewecherl@gmail.com> - 2013-06-18 20:17 +0200
  Re: Identifying a regex Andreas Bergmaier <andber93@web.de> - 2013-06-18 21:14 +0200

csiph-web