Скачать или смотреть How to Pass a String Method in a Map Call in Ruby

Discover how to efficiently use Ruby's map method while passing string methods using symbols for a cleaner approach.
---
This video is based on the question https://stackoverflow.com/q/72953223/ asked by the user 'geckos' ( https://stackoverflow.com/u/652528/ ) and on the answer https://stackoverflow.com/a/72953623/ provided by the user 'John Ledbetter' ( https://stackoverflow.com/u/130641/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to pass a string method in a map call?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Pass a String Method in a Map Call in Ruby

When working in Ruby, it's common to want to transform elements in an array using various methods. A frequent scenario arises when developers aim to capitalize each string in an array of strings using the map method. Traditionally, you might write something like this:

[[See Video to Reveal this Text or Code Snippet]]

While this works perfectly fine, you may find yourself wondering if there's a more concise or elegant way to achieve the same result. This leads us to the question posed: How do you pass a string method in a map call using Ruby?

The Solution

To elegantly pass the string method capitalize using Ruby's map, you can use the following syntax:

[[See Video to Reveal this Text or Code Snippet]]

Breakdown of the Solution

Let's delve deeper into how this works and understand the components involved in this elegant solution:

1. Understanding Symbols

In Ruby, symbols are lightweight, immutable strings that are often used as identifiers, making your code cleaner and more efficient. The :capitalize in the solution is a symbol that represents the capitalize method of the String class.

2. The Ampersand (&) Operator

The ampersand operator is key to this shorthand. By preceding a symbol with &, Ruby interprets it as a cue to convert the symbol into a Proc (a block of code that can be executed).

So when you write &:capitalize, Ruby internally does the following:

[[See Video to Reveal this Text or Code Snippet]]

This means that it looks for the to_proc method defined for symbols and prepares to call the capitalize method on each element of the array you’re mapping over.

3. The Magic of to_proc

The to_proc method is defined on the Symbol class as follows:

[[See Video to Reveal this Text or Code Snippet]]

This piece of code essentially creates a new Proc that takes an object and any additional arguments, then calls the method represented by the symbol on that object.

Example Explained

Given our example with the array ["foo", "bar"]:

[[See Video to Reveal this Text or Code Snippet]]

The map method iterates over each string element ("foo" and "bar").

The &:capitalize syntax converts the :capitalize symbol into a Proc, which in turn calls the capitalize method on each element.

The result is an array of capitalized strings: ["Foo", "Bar"].

Conclusion

Using the &:method_name syntax is a powerful feature in Ruby that allows for cleaner and more readable code. By passing string methods in this way, you're leveraging Ruby's flexibility to write less verbose and more elegant transformations on arrays.

Next time you find yourself needing to apply a method to each element in an array, remember this approach as a handy tool in your Ruby programming arsenal!