Michael Malone
3/24/2009 8:22:00 PM
>> I am new to Ruby and trying to do a find and replace on a text file
>> based on a regular expression. When I step through the code line by
>> line, it appears that the appropriate line in the file is changed, but
>> when I exit the function, the file hasn't been modified. Are in-place
>> edits of files allowed? can you see what it wrong here?
>>
>> Here is the body of the function:
>>
>> def ReplaceGuid(guid)
>> r = nil
>> sconfProj = File.open("myfile.vcproj", "r+").each do |line|
>> m = @guidExp.match(line)
>> if !m.nil?
>> str = m[1]
>> r = %r{#{str}}
>> line.gsub!(r, guid)
>> break
>> end
>> end
>> end
>>
>> Many thanks,
>> Jen
>>
The problem is this: you're reading the contents of your file into
memory, changing the copy in memory and expecting it to propagate to the
physical file. Try this: (though I haven't tested or run it, so there
might be some errors)
def ReplaceGuid(guid)
outfile = File.new("Some_filename", 'w')
found_match = false
IO.read("myfile.vcproj").each_line do |line|
if (@guidExp =~ (line)) && !found_match
line.gsub!($1, guid)
found_match = true
end
outfile.puts line
end
outfile.close
end
That reads in the original and writes the output to a new file. I'm assuming you wanted to stop at the first match, which is what would happen in your original code.
HTH,
Michael
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