Ruby dup/clone recursively

Question

I have a hash like:

h = {\'name\' => \'sayuj\', 
     \'age\' => 22, 
     \'project\' => {\'project_name\' => \'abc\', 
                   \'dur         


        

Answer 1

Here's how you make deep copies in Ruby

d = Marshal.load( Marshal.dump(h) )

Answer 2

This is an answer to a reasonably old question, but I happened upon it while implementing something similar, thought I'd chime in for a more efficient method.

For the simple, two level deep hash like above, you can also do something like this:

d = h.inject({}) {|copy, (key, value)| 
    copy[key] = value.dup rescue value; copy
}

I ran a test on a hash of hashes with 4k elements, each a few hundred bytes, and it was about 50% faster than the Marshal.dump/load

Of course, it's not as complete, as it won't work if you have a hash as, e.g., the value of the 'project_name' field, but for a simple 2 level hash, it works great / faster.

Answer 3

If you are in Rails: Hash.deep_dup

Answer 4

Another alternative is to use the full_dup gem (full disclosure: I am the author of that gem) that handles arrays, hashes, structs, and is extendable to user defined classes.

To use:

require 'full_dup'
# Other code omitted ...
d = h.full_dup

Also note that full_dup handles complex data relationships including those with loops or recursion.

Answer 5

In case the Marchal #dump/load pair isn't work, for rails there is a Hash's method #deep_dup, so you can:

h = {'name' => 'sayuj', 
 'age' => 22, 
 'project' => {'project_name' => 'abc', 
               'duration' => 'prq'}}

h1 = h.deep_dup