In my experience with ruby the balance weighs heavily on the evil side. Clean monkey patching recently, i realised the importance of clean monkey patching in ruby. One of the best, and worst, features of ruby is monkeypatching, extending the languages builtin classes and modules to suit. Sometimes the whole package is meant as a temporary location where experimental features can mature and be distributed early until they get merged into. Why rubys monkey patching is better than land mines. Monkey patching has gone somewhat out of favor of late, especially when you consider the recent work to introduce refinements to ruby. To illustrate monkey patching well make some changes to the good old string core class. This article looks at how to minimize the risk of opening classes, alternatives, and how other languages provide similar capabilities.
Until you hit weird bugs because a patch changed hash. I havent, but it comes really useful when testing, to simulate sideeffecting functions or to silence expected errors and warnings. I read this answer as being misinformed about what monkey patching is, particularly i thought you were saying the ruby continuing class declaration syntax was the only way to monkey patch. Were in the future, and with github and bundler there is now rarely a need to monkeypatch ruby code in your applications monkeypatching is the dangerousyetfrequentlyuseful technique of reopening existing classes to change or add to their behavior. Because ruby is a purely objectoriented language, all methods are true methods and are associated with at least one object. Monkeypatching is the technique of swapping functions or methods with others in order to change a module, library or class behavior. This post is about limiting the scope of monkey patches with rubys refinements. Monkey patching allows you to come up with a quick and dirty solution to a problem, but you should use it very sparingly.
How to monkey patch a class in ruby solid foundation web. 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. How to extend the existing functionality of the fixnum class and add your own methods to it. Many people think that monkey patching is something that is restricted to dynamic languages like ruby and python. 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. Monkey patching hereafter referred to as mp is a technique to override, extend or even suppress the default behavior of. Dec 29, 2017 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.
Nov 29, 2016 ruby programming tutorial class inheritance guide beginner friendly simple ruby tutorial. Monkey patching, gorilla patching or duck patching all refer to the same process of extending or modifying code at runtime without modifying the original source. Learning ruby language ebook pdf download this ebook for free chapters. It was designed and developed in the mid1990s by yukihiro matz matsumoto in japan ruby is dynamically typed and uses garbage collection. This can be used to great effect, for example rails fixnum date extensions, which. Thats where you try to establish an objects suitability for some purpose, using the principle, if it walks like a duck and it quacks like a duck, then it must be a duck.
It supports 32 bit, reversing patches, and patching instance methods. May 29, 20 how to extend the existing functionality of the fixnum class and add your own methods to it. A guide to responsible monkey patching in javascript. In this example, the string class is reopened and the randomize method is added. Jun 17, 2015 ruby is like a sharp knife, it can be extremely effective, but its usually your own fault if you cut yourself. Dave allie monkey patching in ruby isnt always what it seems. Feb 28, 2020 it supports 32 bit, reversing patches, and patching instance methods. Make monkey patching in ruby less risky with refinements. An alternative etymology is that it refers to monkeying about. Before i show you how to override a class, i want to ensure that you understand that monkeypatching is not considered a good practice. Starting off the list for examples of metaprogramming is monkey patching. Ruby language view an objects instance variables ruby. Though using a monkey patch in your ruby code probably isnt your first choice for solving the problem.
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. One of the best, and worst, features of ruby is monkeypatching, extending the languages builtin classes and modules to suit your desires. 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. The issue i find with just swapping out code is that i dont like servers that live very long. Im actually really surprised go doesnt just let you add methods to arbitrary types that you dont own. Monkeypatching, like many tools in the programming toolbox, can be used both for good and for evil. Let foo be a python package, built on top of another python package bar. Mar 10, 2012 this videos shows you what monkey patching is in ruby. Ruby language view an objects instance variables rip tutorial. Its a very simple helper that adds html comments to the rendered source, so that you can inspect it easily in your browsers developer toolbar. Yes, i understand that you can use ruby without monkey patching but what i am wondering if the chief reason developers reach for ruby is there love for monkey patching. Learning ruby language ebook pdf rip tutorial stack.
I would like to know the exact meaning of monkey patching in ruby. Where to put code when monkey patching stack overflow. Ruby uses the case keyword for switch statements as per the ruby docs case statements consist of an optional condition, which is in the position of an argument to case, and zero or more when clauses. And that could lead to side effect if we are not careful. Jul 11, 2008 ruby s open classes are powerful but can easily be misused. Interfaces are statically checked python duck typing.
In todays tutorial well be looking at monkey patching in ruby. I havent, but it comes really useful when testing, to simulate sideeffecting functions or to silence. I wrote a couple of examples and put those in the readme. Ruby is like a sharp knife, it can be extremely effective, but its usually your own fault if you cut yourself. Ruby is an interpreted, highlevel, generalpurpose programming language. When in vanilla ruby, a gem, for instance, you define a module in some file you are requiring and then include or. As explained in the ruby programming language book, many languages distinguish between functions, which have no associated object, and methods, which are invoked on a receiver object. Sometimes foo may wish to extend the bar package by adding features e. 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.
Monkey patching, like many tools in the programming toolbox, can be used both for good and for evil. Yes, its a weird name, but its a powerful and dangerous tool. 1 2 3 4 5 6 7 8 9 10 11 12 14 15 16 17 18 19 20 21. Ruby language initializing a 2d array ruby tutorial. Recursive monkey patching for python motivating use case. Monkey patching is the process of extending or modifying the runtime code of dynamic languages e.
Monkey patching in python is often see as being one of those things you should never do. For example, if monkeypatching the sidekiqtesting gem class you should mirror the file structure. There are some people with strong opinions about it. Lets first recap how to initialize a 1d ruby array of integers. 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. Monkey patching, for anyone who doesnt know, refers to the practice of extending or modifying existing code by changing classes at runtime. The purpose of ruby refinements is to provide a solution by scoping changed behavior to the very specific area of code you choose. Some do regard it as a useful necessity you cant avoid in order to patch bugs in third party code.
If monkey patching is permitted in both ruby and python, why. A common pattern is to use an inline, or trailing, if or unless. Were using capistrano, but its managing docker containers. Jul 27, 2016 monkey patching has been used for a long time for modifying code behavior, but it creates side effects in code elsewhere that ends up affected by the modified code. Id father rather have everything to be temporary and useonce. Its possible for a program to modify itself at runtime, which allows us to implement cool tricks like monkey patching. Also id advise to use a module to wrap the monkey patch. Sometimes youre doing it the right way for the wrong reasons, other times you are doing it just flat out wrong. It was designed and developed in the mid1990s by yukihiro matz matsumoto in japan.
Ruby programming tutorial class inheritance guide beginner friendly simple ruby tutorial. Pragmatic uses of monkey patching in javascript sitepoint. The first when clause to match the condition or to evaluate to boolean truth, if the condition is null wins, and its code stanza is executed. This practice, known as monkey patching, is common in the ruby world, and since ruby 2, its been possible. This is my take on what i consider to be best practice. According to the creator, ruby was influenced by perl, smalltalk, eiffel. A monkey patch is a way for a program to extend or modify supporting system software locally affecting only the running instance of the program. Monkey patching is an object oriented programming technique that allows developers to.
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. Lets look at how go functions work and how we can modify them at runtime. The decorator pattern and monkey patching have yet another name, coined by ruby hackers who decided that they needed a name that reflected their use of duck typing. This videos shows you what monkey patching is in ruby.
To be fair monkey patching in ruby and js land is also unsafe and can be nutty but they dont have compilers. Smalltalk, javascript, objectivec, ruby, perl, python, groovy, etc. The question is where, on balance, such tools tend to be most used. 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. That is not true however, as computers are just dumb machines and we can always make them do what we want. So you search for how to moneykeypatch a class in ruby.
With this in mind it is worth thinking about whether we are comfortable monkey patching nearly every object in our system. Is it doing something like the following, or is it something else. Rubys open classes are powerful but can easily be misused. If monkey patching is permitted in both ruby and python. 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.
It supports multiple programming paradigms, including procedural, objectoriented, and functional programming. Making methods immutable in ruby or, death to monkey patching. 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. The word guerrilla, homophonous with gorilla or nearly so, became monkey, possibly to make the patch sound less intimidating. Ruby programming tutorial class inheritance guide beginner.
Others will argue though that with so much software being open source these days that you should simply submit a. Active support online video tutorial by thoughtbot. Because ruby is a purely objectoriented language, all methods are true methods and are. Jun 17, 2010 monkey patching is the process of extending or modifying the runtime code of dynamic languages e. Guerillapatch is a ruby gem to ease the transition to ruby 2.
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