Ruby writing to a file in memory (not actually writing to it)

Question

So I have this program that works with passing around a string (this string is the path of the file it is supposed to read)

Now I have a method that has to open that file. change the text with Gsub and than output that file again (The original file can't be edited) but I need to eventually output that changed file

this is the method i'm using to change my file (simplified)

def self.changeFile(myfile)
myfile = @path

doc = File.open(myfile)
text = doc.read

text.gsub!("change" , "changed")

return text

the problem with this is I get the entire file as string returned. My other methods work with the input of a "string" pathname

So my question is is there anyway I can write my text to the file I changed in the memory, so without actually changing the original file?

I was thinking about using "Tempfile" or "StringIO" but I don't know if this is the right thing to go about

All Help is appreciated

Do you want to create another file with changed text from original file? If so do you want to make it temp file or an ordinary file? — Maxim Pontyushenko, Apr 08 '16 at 10:36
@Maxim Pontyushenko Yes I want to create a file with the total new file (the one that is changed) but i don't want to WRITE — FroggyFreshh, Apr 08 '16 at 12:20
*My other methods work with the input of a "string" pathname*--That rules out StringIO because a StringIO does not have a pathname. *but i don't want to WRITE*--To create a file, you have to write to the file. Tempfile just creates a name for the file that won't clash with any existing filenames. If you want to delete the Tempfile after you are done making all your alterations and have printed out the file, then that would be the way to go. Otherwise, you could create a new file with the same name as the original file plus something like "altered" added to the end of the filename. But .... — 7stud, Apr 08 '16 at 12:55
...that could end up overwriting an existing file. To avoid that, you could create a new directory and add the new files to it. — 7stud, Apr 08 '16 at 12:58

score 1 · Answer 1 · answered Apr 08 '16 at 10:41

1

You can use temple for this:

def self.changeFile(myfile)
  myfile = @path
  tempfile = Tempfile.new("changed")
  tempfile << File.open(myfile).read.gsub("change" , "changed")
  tempfile.close
  tempfile.path
end

answered Apr 08 '16 at 10:41

Maxim Pontyushenko

2,983
2
25
36

Do i do "return tempfile" and than work with the tempfile in my other methods ? – FroggyFreshh Apr 08 '16 at 10:56
@FroggyFreshh You don't need to use `return` because the last line is what returned by default in ruby methods. So you will have tempfile path as returning value of this method. – Maxim Pontyushenko Apr 08 '16 at 13:49
Watch out - the file will be deleted when tempfile is garbage collected - which could happen at any point – Frederick Cheung Apr 08 '16 at 14:14
@FrederickCheung true. – Maxim Pontyushenko Apr 08 '16 at 14:21

Ruby writing to a file in memory (not actually writing to it)

1 Answers1