TempfileFor

Easily create temporary files for in-memory data, modify the file, and get the full content returned.

Add this line to your application's Gemfile:

gem "tempfile_for"

And then execute:

$ bundle

Alternatively, you can of course install it without using bundler via:

$ gem install tempfile_for

TempfileFor is a very tiny gem, but it can save you lines of ugly code.

To get a quick introduction into what TempfileFor does, check this out:

Tempfile.for("string1") { |tempfile| `echo -n ', string2' >> #{tempfile.path}` }
# => "string1, string2"

Say, you have some in-memory data, like an image you fetch from an URL - and you want to somehow modify it partially like e.g., add or remove IPTC tags, or scale it, etc. Often, the gems used to modify images or other media files require a path to the file to be able to modify it.

This is easy thanks to TempfileFor:

data = RestClient.get("http://example.com/image.jpg")

image = Tempfile.for(data) do |tempfile|
  # Modify the tempfile directly or using tempfile.path and get the modified content returned.
  # Tempfile takes care about flushing the file's modifications and rewinding, etc.
end

If you want to use TempfileFor without initial data, simply use:

Tempfile.blank { |tempfile| `echo -n data >> #{tempfile.path}` }

In case you need the tempfile object itself, because you e.g. don't want to load it into memory, add :read => false to either Tempfile#for or Tempfile#blank

Tempfile.for("string", :read => false) { |tempfile| ... } # => #<File:/tmp/tempfile...>
Tempfile.blank(:read => false) { |tempfile| ... } # => #<File:/tmp/tempfile...>

TempfileFor preserves the encoding of the supplied data. Thus, the following code

Tempfile.for("string1".encode(Encoding::ISO_8859_1)) { ... }

will return a string encoded as ISO-8859-1. If you use the blank method, you can supply the desired encoding via

Tempfile.blank(:encoding => Encoding::BINARY) { ... }

will return a string encoded as binary.

You can pass a :suffix => "..." option to all methods, such that

Tempfile.for("data", :suffix => ".jpg")
Tempfile.blank(:suffix => ".jpg") { ... }

will create tempfiles having a .jpg suffix.

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request