From: Max Ischenko <max@...>
Date: 2001-03-02T23:40:02+09:00
Subject: [ruby-talk:11898] Re: rewrite with Ruby


At Fri, 2 Mar 2001 21:45:48 +0900 Hugh Sasse Staff Elec Eng wrote:

> On Fri, 2 Mar 2001, Max Ischenko wrote:

>> I have the following Ruby code:
>> 
>> def Mutt.afterConfigure
>>       system("perl -i -p -e 's/^#define DEBUG/#undef DEBUG/' config.h")
>        [...]
>> 
>> Now, I want to write a generic function that will make changes to a file,

> How would one make it really generic?  Ruby has -i as well, so how can one
> get at it to do:
>        ruby -i.bak -p -e 'gsub(/^#define DEBUG/, "#undef DEBUG/") config.h
> in an elegant way,  within a program? Is it worth raising  an RCR for open
> and IO to have some means to provide this backup facility?

I end up with this:


patchFile('/tmp/config.h', {
	'ICONV' => 'iconv',
	'#define (DEBUG|USE_DOTLOCK)' => nil,
})
 
def patchFile(fname, subs)
  if not FileTest.exist? fname or
    not FileTest.readable? fname
    not FileTest.writable? fname
    raise "Can't patch file #{fname}"
  end
  lines = IO.readlines(fname)
  aFile = File.open(fname, 'w')
  lines.each {|x|
    line = x
    subs.each {|key,val|
      next unless x =~ key
      if not val
        puts "Delete line #{x}"
        line = nil
      else
        line = x.gsub(key, val)
        puts "Change line #{x} to #{line}"
      end
      break
    }
    aFile.print line if line
  }
  aFile.close
end

PS: I have another version, which accept block as argument,
but it seems to be too complex.

-- 
programming, /n./: The art of debugging a blank sheet of paper.