From: Eric DUMINIL <eric.duminil@...>
Date: 2007-07-18T18:37:33+09:00
Subject: Re: Easily parsing a string to retrieve values and assign them to a variable/symbol.

I think that what you describe is exactly what I implemented as
searching_reg_exp.

For example searching_reg_exp corresponding to
'ftp://ftp.org/DATA/{user_name}/{year}/{month}-{day}.txt' is:
/^ftp:\/\/ftp\.org\/DATA\/(.+)\/(.+)\/(.+)\-(.+)\.txt$/

if you want it to be non-greedy, it would be:
/^ftp:\/\/ftp\.org\/DATA\/(.+?)\/(.+?)\/(.+?)\-(.+?)\.txt$/

Or did I get you wrong?

I wouldn't choose the eval() path for security reasons, as you mentioned it...
'foo{system("rm -rf ~/")}'  would be pretty bad!

Which method are you thinking about when you wrote "something similar
and less dangerous"?

Bye,

Eric






On 18/07/07, SonOfLilit <sonoflilit@gmail.com> wrote:
> There is an option for regexen to lazily evaluate. So you could
> represent a regex-free string with a regex like that, then whenever
> you need it - evaluate the regex, convert it to a string and use it
> :).
>
> OR you could store the string 'stuff \#{name}' and later #eval() it or
> something similar and less dangerous when you need it's evaluation.
>
> Aur
>
> On 7/18/07, Eric DUMINIL <eric.duminil@gmail.com> wrote:
> > Hi
> > Thanks for the appreciation!
> > Your suggestion is interesting, even though I'm not sure it would work, because:
> >
> > 'foobar'.parse_for_variables('foo#{name}','#{')
> > => {:name=>"bar"}
> >
> > works, but when you use it with double quotes string:
> >
> > 'foobar'.parse_for_variables("foo#{name}",'#{')
> > NameError: undefined local variable or method `name' for main:Object
> >
> > it already tries to evaluate "name" inside the string...
> > so either you get retrieval or assignment right, but not both :(
> > Anyway, assignment is not that big a deal:
> >
> > (irb) h={:year=>"2005", :user_name=>"mike", :day=>"15", :month=>"10"}
> > => {:year=>"2005", :user_name=>"mike", :day=>"15", :month=>"10"}
> >
> > (irb) 'ftp://ftp.org/DATA/{user_name}/{year}/{month}-{day}.txt'.gsub(/\{(.+?)\}/){h[$1.intern]}
> > => "ftp://ftp.org/DATA/mike/2005/10-15.txt"
> >
> > Best regards,
> >
> > Eric
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > On 18/07/07, Pe�a, Botp <botp@delmonte-phil.com> wrote:
> > > From: Eric DUMINIL [mailto:eric.duminil@gmail.com]
> > > # For example, I would not know which file I should retrieve on:
> > > #  'ftp://ftp.org/DATA/mike'
> > > # but
> > > #  'ftp://ftp.org/DATA/{user_name}/{year}/{month}-{day}.txt' would do
> > > # just fine, so that I could, for example, get this hash:
> > > #  {:year=>"2005", :user_name=>"mike", :day=>"15", :month=>"10"}
> > > # for this filename:
> > > #  'ftp://ftp.org/DATA/mike/2005/10-15.txt'
> > >
> > > very nice.
> > > but would it be more practical if we delineate a variable just like we used to in ruby inline string; ie, use #{var} instead of just {var}
> > >
> > > this would be handy like, if i want to rename or move all folders under /mike/2005/ to /mike/2007/ eg.. the retrieval and assignment string just stay the same...
> > >
> > > kind regards -botp
> > >
> > >
> >
> >
>
>