Monkey patching ruby hash

Ruby is like a sharp knife, it can be extremely effective, but its usually your own fault if you cut yourself. It is a powerful technique that has become popular in the ruby community at least in part because the ruby language makes it so easy. Eventually i would like to freeze array and hash literals in source code itself, but i think this is a good first step. The humble ruby hash has a few tricks up its sleeve. What is monkey patching and why is it so abhorrent. The backtrace provided by ruby shows the exception is raised by line 908 of ftp. In ruby, a monkey patch mp is any dynamic modification to a class and is often used as a synonym for dynamically modifying any class add new or overwrite existing methods at runtime. The problem of this solution is that the monkeypatch will be shared among all the instances of the monkeypatched class in our case the hash class. Hopefully, after reading this post youll have a better idea what youre doing, and.

But just like any of ruby s sharp edges, you have to take extra care when you use them. These are two different concepts programming approaches. A hash includes the enumerable module, which provides several iteration methods, such as. Its important that you know this because if you are ever working with an older version of ruby anything before ruby 1. This practice, known as monkey patching, is common in the ruby world, and since ruby 2, its been possible to mitigate some of the risks using refinements. Pragmatic uses of monkey patching in javascript sitepoint. How to use rubys refinements feature to create a library that can be. The name monkey patching basically comes from older times where you needed to do hot patches fixes or changeinject new functionality, especially into 3rd party code which you depended on, but couldnt change the original. The term monkey patch seems to have come from an earlier term, guerrilla patch, which referred to changing code sneakily and possibly incompatibly with other such patches at runtime.

However, a powerful tool in the wrong hands will cause endless amounts of pain and suffering. Recursively sort ruby hash by key daniel doezemas blog. Ruby will understand that the hash class already exists and that you are. Replace methods classes attributes functions at runtime, e.

In todays tutorial well be looking at monkey patching in ruby. In ruby, the term monkey patch was misunderstood to mean any dynamic modification to a class and is often used as a synonym for dynamically modifying any class at runtime. Unfortunately, the majority of popular articles are very controversial, and i feel obliged to write a response on one of the so called pros of ruby. It also made thousands of rubyists think that monkey patching is great. Heres a quick and easy way to sort a ruby hash by its keys. Some im not so crazy about and its usually areas where they tried to copy perl. Far from being a dumb keyvalue system, the hash object gives you the power to do some very interesting and sophisticated things. Depending on the amount of data in your hash, your mileage will vary, but i find this a pretty serviceable addition to the hash class.

Associates the value given by value with the key given by key. Hashdiff is a ruby library to compute the smallest difference between two hashes. Sometimes youre doing it the right way for the wrong reasons, other times you are doing it just flat out wrong. Ruby language iterating over a hash example a hash includes the enumerable module, which provides several iteration methods, such as. Until you hit weird bugs because a patch changed hash. Ruby eases the possibility to monkeypatch due to the fact that ruby classes or. Ruby hash monkeypatch methods relating to the hashs default. It was designed and developed in the mid1990s by yukihiro matz matsumoto in japan. Apply the result of a patch at runtime to the state in memory, instead of the source code on disk. Tests whether two hashes are equal, based on whether they have the same number of keyvalue pairs, and whether the keyvalue pairs match the corresponding pair in each hash. Monads in yesterdays post, i introduced monadt, a gem that adds algebraic data types adts and monads to ruby. Whenever you monkey patch a class you are potentially creating a headache at some point in the future when things go wrong. Turns out there is not a built in way in ruby to do this.

Overall ive been pretty happy with its features, ecosystem and libraries for web development, however my previous dabbles into python have left me longing for a yet unimplemented feature. Ruby is an interpreted, highlevel, generalpurpose programming language. Also called associative arrays, they are similar to arrays, but where an array uses integers as its index, a hash allows you to use any object type. Why rubys monkey patching is better than land mines. Ruby makes it easy to extend its builtin classes, which can be very convenient and lead to more readable codebut it can also be dangerous. Unlike arrays, hashes can have arbitrary objects as indexes. There are a few posts out there on how to achieve this, but most resort to monkey patching the hash class or created a new subclass, like the answer in this so question.

I would like to know the exact meaning of monkey patching in ruby. Ruby is dynamically typed and uses garbage collection. Because ruby is an interpreted language objects are open and can be modified at runtime. Somebody can say that adding functionality to core classess even through refinements is a bad practice. A hash is a dictionarylike collection of unique keys and their values. Jul 11, 2008 ruby s open classes are powerful but can easily be misused. This includes the default ruby classes like string, array, or hash. Let me know if you have any other approaches to this problem. It supports multiple programming paradigms, including procedural, objectoriented, and functional programming. Monkey patching in python dynamic behavior geeksforgeeks. How to monkey patch a class in ruby solid foundation web.

Ruby provides us with a wealth of powerful tools to work with. Jun 17, 2015 monkey patching in particular is an extremely powerful tool. The word guerrilla, homophonous with gorilla or nearly so, became monkey, possibly to make the patch sound less intimidating. Ruby s open classes are powerful but can easily be misused.

Lets make a ruby hash map method that returns a hash instead. The method can be easily modified and placed into a utility class if youd prefer. How to monkey patch a class in ruby posted by weston ganger sometimes you may need to override a method or add a new one to an existing class from a library or gem using a monkey patch. Deliberately provocative title, but makes a well considered case for restrained use of monkey patching in ruby. The reason i want this feature is i think we can reduce some object allocations, and once guilds are implemented, easily create immutable data. The ability to sort recursively and provide a custom sort block are also available features. Monkey patching in python dynamic behavior in python, the term monkey patch refers to dynamic or runtime modifications of a class or module. To illustrate monkey patching well make some changes to the good old string core class. An alternative etymology is that it refers to monkeying about. Add compilation flags to freeze array and hash literals ruby. Hopefully, after reading this post youll have a better idea what youre doing, and youll be monkey patching the right way for the right reasons. Sep 09, 2018 the problem of this solution is that the monkeypatch will be shared among all the instances of the monkeypatched class in our case the hash class.

Make monkey patching in ruby less risky with refinements. Rubys open classes are powerful but can easily be misused. Monkey patching in particular is an extremely powerful tool. Monkey patching hereafter referred to as mp is a technique to override, extend or even suppress the default behavior of a code segment without changing its original. It may be or maybe not true for large enterprisey systems with tens of juniors fixing your code here and there and some contractor just running through it wildly. I wouldnt say monkey patching is bad, its more like a should avoid practice, there are. The difference between this library and others is that all monkey patching is performed in an optin way. If youre concerned about monkeypatching, consider including andor extending this functionality into one of your own classes or instances. This includes the standard ruby classes like string, array or hash. Cultural norms around monkey patching seem to me to be one of the core differences. Monkey patching, for anyone who doesnt know, refers to the practice of extending or modifying existing code by changing classes at runtime. This modified text is an extract of the original stack overflow documentation created by following contributors and released under cc bysa 3. Modifyextend behaviour of a thirdparty product without maintaining a private copy of the source code.

Hi, some of you might have noticed an article i published last week on why i currently feel lonely in the ruby community because i dont share a. So, ruby already has a hash class, the instances of which youve been working with in the past two units. Getting a stronger ruby community with a different mindset. You get confused about which code actually ran, so you cant. Were in the future, and with github and bundler there is now rarely a need to monkey patch ruby code in your applications monkey patching is the dangerousyetfrequentlyuseful technique of reopening existing classes to change or add to their behavior. Forget about that strange name and lets call it changing the behavior of the original code. Advanced ruby hash techniques honeybadger developer blog. Monkey patching is the practice of reopening and modifying preexisting classes. In python, we can actually change the behavior of code at runtime. Hashes enumerate their values in the order that the corresponding keys were inserted.

Duck typing a programming concept that is primarily concerned with the methods that can be run on an object rather than the class of the object. One thing ive never been crazy about is monkey patching. Yes thats right, you can actually reopen any class and change how it works. Cultural norms around monkey patching seem to me to be one of the core differences between the ruby and python communities. However, just because a tool is powerful, does not make it the right tool for the job. In past versions of ruby, you could not rely on hashes maintaining order.