Ruby Hash destruction like from Javascript world (and reconstruction)

You're probably familiar with destructuring assignments in JavaScript, which allow you to easily extract values from arrays or objects. In Ruby, destructuring has traditionally been a bit more verbose, requiring several lines of code. However, with recent advances, you can now achieve JavaScript-like hash destruction and restructuring in Ruby. In this article, we'll explore how you can use these techniques to simplify your code and improve readability.

Ruby Hash Destruction

Traditionally, extracting values from a hash in Ruby involved accessing individual keys and assigning them to variables by hand. With the new syntax, however, you can achieve the same result with a single line of code. Let's look at an example:

some_data = { a: 'a new word', b: 22, c: 'Some string', d: [55, 66, 77] }
some_data => { a:, b:, d: my_special_array, c: my_c_string }
p [a, b, my_c_string, my_special_array] 
# => ["a new word", 22, "Some string", [55, 66, 77]]

In the code above, we have a some_data hash that contains different values. By using the new hash destruction syntax, we can extract specific keys and assign them directly to variables. The resulting code is concise and easy to read.

Restructuring Hashes

In addition to destructuring, you can also restructure hashes in a more concise manner using the new syntax. Consider the following example:

{ ff: 'fff', data: { a: 'new record' }, code: 200, response_status: 'OK', aa: 'aa', bb: 'bb' } => { data:, code:, response_status: status_text, **rest }
p data # => {a: 'new record'}
p code # => 200
p status_text # => "OK"
p rest # => {:aa=>"aa", :bb=>"bb"}

In this example, we have an initial hash with multiple key-value pairs. Using the restructuring syntax, we extract certain keys, renaming some of them in the process. The double splat operator (**) allows us to capture the remaining key-value pairs that were not explicitly mentioned.

Destructuring Arrays

In addition to hashes, you can also destructure arrays in Ruby. Let's take a look at a simple example:

arr = [1, 2, 3, 4, 5, 6]
arr => [left, second, b, *rest]
p left # => [1, 2]
p second # => 3
p b # => 4
p rest # => [5]

In the code above, we have an array called arr with multiple elements. Using array destructuring syntax, we extract certain elements from the array and assign them to variables. The asterisk (*) notation captures the remaining elements of the array.

Grouping Elements

In some cases, you may want to group elements as you destructure arrays. Ruby provides an intuitive syntax for doing this. Consider the following example:

arr = [1, 2, 3, 4, 5, 6]
arr => [*left, 3, 4, *rest]
p left # => [1, 2]
p rest # => [5, 6]

In this example, we group the elements of the array using square brackets ([]). The asterisk (*) notation allows us to capture multiple elements at once, which simplifies the restructuring process.

Reconstructing Hashes

Apart from destructuring, you can also reconstruct hashes using a concise syntax. Let's look at an example:

aa = 'a'
bb = 'b'
my_new_hash = { aa:, bb: } # equals to { aa: aa, bb: bb }
p my_new_hash 
# => {:aa=>"a", :bb=>"b"}

In this snippet, we assign values to the variables aa and bb. Using the new syntax, we can reconstruct a hash using the variable values as both keys and values. This approach eliminates repetitive key-value assignments and improves code readability.

Summary

In this article, we explored how recent advances in Ruby have made hash breaking and rebuilding easier and clearer. By using JavaScript-like syntax, you can easily extract values from hashes and arrays, improving the readability and maintainability of your code. These techniques provide an efficient way to work with complex data structures in Ruby, making your development process more productive.