From: Dan George <endege@...>
Date: 2007-09-20T04:35:09+09:00
Subject: Re: YAML & readlines & modify text files

On Sep 19, 9:22 pm, Stefano Crocco <stefano.cro...@alice.it> wrote:
> Alle mercoled� 19 settembre 2007, Dan George ha scritto:
>
>
>
> > On Sep 19, 5:27 pm, Stefano Crocco <stefano.cro...@alice.it> wrote:
> > > Alle mercoled� 19 settembre 2007, Dan George ha scritto:
>
> > > I'm not at all sure I understand correctly what you want to do. I think
> > > you want to replace the line under
>
> > > Name-line: Name01
>
> > > with some text containing a string taken from the Name01 entry in the
> > > yaml file. Is it correct? If it isn't, then please explain better what
> > > you mean. Otherwise, read on.
>
> > > In my opinion, you're storing data in the YAML file in the wrong way,
> > > because, at each iteration, name contains only one pair of
> > > name/replacement string, which forces you to iterate over all the files
> > > for each document in the YAML file (and also makes the replacing code
> > > more complicated). I think your YAML file should contain a single hash,
> > > with the names as keys and the replacement strings as values:
>
> > > ---
> > > Name01: N01
> > > Name02: N02
>
> > > Then, you can do the following (untested)
>
> > > require 'yaml'
> > > lnk = 'blabla.something.'
> > > op = '&=bla'
> > > hash = File.open('name.yaml'){|f| YAML.load f}
> > > Dir.glob('**/.txt').each do |path|
> > >   lines = File.readlines(path)
> > >   lines.each_with_index do |line, i|
> > >     if line.match(/Link-line/)
> > >       match = lines[i-1].match(/Name-line:\s(.*)$/)[1]
> > >       line.gsub!(/Link-line.*/, 'Link-line: '+ lnk+hash[match[1]]+
> > >              op) if match and hash.has_key?(match[1])
> > >     end
> > >   end
> > >   File.open(path,'w'){|f| f.write lines}
> > > end
>
> > > When iterating on the lines, the block is passed not only the line, but
> > > also the line number. This way, when you meet a Link-line line, you can
> > > access the corresponding name-line using its index. It then matches the
> > > previous line with a regexp to extract the name from it and stores the
> > > result in the match variable. If match is not nil (i.e if the name line
> > > had the expected format) and the name is included in hash, the
> > > replacement is performed (of course, you can skip this test if you're
> > > confident enough in the format of the files and in the contents of the
> > > yaml file)
>
> > > I hope this helps
>
> > > Stefano
>
> > You are correct, that is what I want!
>
> > I tryied what you suggested but I get some weird errors:
>
> > new.rb:45: undefined method `[]' for nil:NilClass (NoMethodError)
> >    from D:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
> > `each_with_index'
> >    from new.rb:43:in `each'
> >    from new.rb:43:in `each_with_index'
> >    from new.rb:43
> >    from new.rb:41:in `each'
> >    from new.rb:41
>
> > Line 45 is:       match = lines[i-1].match(/Name-line:\s(.*)$/)[1]
> > Line 43 is:       lines.each_with_index do |line, i|
> > Line 41 is:       Dir.glob('**/*.jad').each do |path|
>
> > I don't get it, as far as I can tell the code is ok...
>
> I think it's because of a mistake in my code: the [1] part of line 45
> shouldn't be there (it's a leftover from a previous version of the code).
> If I'm right, the string doesn't match the regexp, so lines[i-1].match(...)
> returns nil, which doesn't have a [] method, leading to the error you get.
> Avod to call nil.[] is the reason for the conditional at the end of the
> following line (note that the conditional checks that match is not nil before
> trying to extract an element from it), but this is useless if I call it on
> the line before. Removing that [1] from line 45 should solve your porblem.
>
> However, if you found this mistake, it may mean that there's something amiss
> in either your .txt files or your yaml file (see the end of my previous
> post).
>
> Stefano

Stefano thanks for your replies so far.

That did. The code executes ok but "match = lines[i-1].match(/Name-
line:\s(.*)$/)" always returs nil (I did "puts match" after it) and I
don't understand why. I checked my txt files and my yaml file and they
are ok.

txt file has:

Name-line: New York
Link-line: etc

and YAML file has:

---
New York: NY

So the value from the Name is equal to the one in the YAML file. Am I
still missing something obvious?

Sorry if some things seem so obvious that I should understand them but
I'm just a beginner, started a couple of weeks back and the only way
for me to learn is from examples that I try myself and it annoys to
see that something simple gives me so much trouble but I don't want to
quit either :).