I have some functions that work on strings for some business logic.
Should I put them as normal functions in helper files and access them as:
custom_function(my_var)
Or is it better to extend the string class and access them as:
my_var.custom_function
I find extending built-in objects like that confusing. You move from project to project and wonder why you cannot do my_var.foo only to realize that foo was a function that your colleague wrote.
Just imagine you added extension methods indiscriminately. Now you have to copy a block of code from one project to another and spend time scratching your head about the extension methods.
Related
So I'm learning RoR and I have to 3 services that calls an API with the same structure and i want to know if i can do it with a parent class and then work with the parent class to save code.
Thanks!
Yes. This may work if you can define a method with fewer arguments, which builds that structure for the API call.
Approaches are:
Put that common method in a base class which the other classes inherit from.
Put that common method in a module as a mix in.
Write a class to handle the call to the API, which builds the structure.
I don't think you have an "isa" relationship from the sound of it. So unless you do, 2 is preferred to 1. You can only inherit from one class, so mixins are more flexible.
Approach 3 is a good idea. You can have internal methods for the hostname and other constants for your API call.
This can be combined with the other approaches as you can use the Aggregation pattern to aggregate the API object in the other classes. That might or might not make sense. It might be just as well as the other classes have methods which instantiate the class in approach 3 and call it.
I'm making a method inside a Ruby on Rails app called "print" that can take any string and converts it into a png. I've been told it's not good to make class methods for base ruby classes like String or Array or Hash, etc. so "some string to print".print is probably not something I should do.
I was thinking about making a subclass of String called Print (class Print < String) and storing it in my lib/assets folder. So it would look like: Print.new("some string to print"). So my question is, am I on the right track by 1) creating a sub-class from String and 2) storing it in lib/assets?
Any guidance would be greatly appreciated!
Answers to your question will necessarily be subjective because there are always be many answers to "where should I put functionality?", according to preference, principle, habit, customs, etc. I'll list a few and describe them, maybe add some of my personal opinions, but you'll ultimately have to choose and accept the consequences.
Note: I'll commonly refer to the common degenerate case of "losing namespacing scope" or "as bad as having global methods".
Monkeypatch/Extend String
Convenient and very "OO-message-passing" style at the cost of globally affecting all String in your application. That cost can be large because doing so breaks an implicit boundary between Ruby core and your application and it also scatters a component of "your application" in an external place. The functionality will have global scope and at worst will unintentionally interact with other things it shouldn't.
Worthy mention: Ruby has a Refinements feature that allows you to do do "scoped monkeypatching".
Worthy mention 2: Ruby also lets you includes modules into existing classes, like String.class_eval { include MyCustomization } which is slightly better because it's easier to tell a customization has been made and where it was introduced: "foo".method(:custom_method).owner will reveal it. Normal Monkeypatching will make it as if the method was defined on String itself.
Utils Module
Commonly done in all programming languages, a Util module is simply a single namespace where class methods/static methods are dumped. This is always an option to avoid the global pollution, but if Util ends up getting used everywhere anyways and it gets filled to the brim with unrelated methods, then the value of namespacing is lost. Having a method in a Util module tends to signify not enough thought was put into organizing code, since without maintenance, at it's worst, it's not much better than having global methods.
Private Method
Suppose you only need it in one class -- then it's easy to just put it into one private method. What if you need it in many classes? Should you make it a private method in a base class? If the functionality is inherent to the class, something associated with the class's identity, then Yes. Used correctly, the fact that this message exists is made invisible to components outside of that class.
However, this has the same downfall as the Rails Helper module when used incorrectly. If the next added feature requires that functionality, you'll be tempted to add the new feature to the class in order to have access to it. In this way the class's scope grows over time, eventually becoming near-global in your application.
Helper Module
Many Rails devs would suggest to put almost all of these utility methods inside rails Helper modules. Helper modules are kind of in between Utils Module and Private Method options. Helpers are included and have access to private members like Private Methods, and they suggest independence like Utils Modules (but do not guarantee it). Because of these properties, they tend to end up appearing everywhere, losing namespacing, and they end up accessing each other's private members, losing independence. This means it's more powerful, but can easily become much worse than either free-standing class/static methods or private methods.
Create a Class
If all the cases above degenerate into a "global scope", what if we forcibly create a new, smaller scope by way of a new class? The new class's purpose will be only to take data in and transform it on request on the way out. This is the common wisdom of "creating many, small classes", as small classes will have smaller scopes and will be easier to handle.
Unfortunately, taking this strategy too far will result in having too many tiny components, each of which do almost nothing useful by themselves. You avoid the ball of mud, but you end up with a chunky soup where every tiny thing is connected to every other tiny thing. It's just as complicated as having global methods all interconnected with each other, and you're not much better off.
Meta-Option: Refactor
Given the options above all have the same degenerate case, you may think there's no hope and everything will always eventually become horribly global -- Not True! It's important to understand they all degenerate in different ways.
Perhaps functionality 1, 2, 3, 4... 20 as Util methods are a complete mess, but they work cohesively as functionality A.1 ~ A.20 within the single class A. Perhaps class B is a complete mess and works better broken apart into one Util method and two private methods in class C.
Your lofty goal as an engineer will be to organize your application in a configuration that avoids all these degenerate cases for every bit of functionality in the system, making the system as a whole only as complex as necessary.
My advice
I don't have full context of your domain, and you probably won't be able to communicate that easily in a SO question anyways, so I can't be certain what'll work best for you.
However, I'll point out that it's generally easier to combine things than it is to break them apart. I generally advise starting with class/static methods. Put it in Util and move it to a better namespace later (Printer?). Perhaps in the future you'll discover many of these individual methods frequently operate on the same inputs, passing the same data back and forth between them -- this may be a good candidate for a class. This is often easier than starting off with a class or inheriting other class and trying to break functionality apart, later.
I have a class that I want to split across multiple files. I tried using categories, but can't figure out how to make it work.
My class is named UserManager and I want to create UserManager+Amazon and UserManager+Facebook.
The problem is that I do need to access private properties and/or methods in UserManager+Amazon that are implemented in UserManager+Facebook, and vice-versa.
How can I extract methods outside the main UserManager.m file, while maintaining the access to private stuff?
EDIT: #Avi has an excellent idea below, although I have not tested it.
I have also just discovered a solution: Properties for Class and Its Subclasses Only
It works with categories and subclasses. I have tested it with my code and it works. It uses a class extension on the BaseClass.h, complete with an implemented example immediately below the accepted answer.
OLD:
I've been struggling with this recently as well.
My current idea is to create a third category UserManager+Private that implements all of the private methods and handles the properties via associated objects (http://nshipster.com/associated-objects/).
It feels very unwieldy, but it might work for you. I would still be interested in a better solution if one exists.
I'm relatively new to rails, but I've made a few basic CRUD apps. However, this time, I'm making something different, and I'm not sure how to organize it.
It's essentially a one page app. The user fills out a form, and the code does some calculations based on those values. I have all the code written, but it's all just sitting in the controller. I'm assuming that this isn't correct.
There are two parts:
Using an external API, 2 constant arrays are generated. I need these variables to be global, or at least accessible for the calculator function.
I have a function that takes some inputs from the form that also calls other functions. A simplified version is below. I could put all the code into one function if that's necessary. I have them separate just so that the code is more readable.
def calc(input)
func1(input)
func2(input)
# do more stuff
return answer #I need to show this in the view
end
def func1(a)
end
def func2(b)
end
So, where should I put each part of this code?
To make your controllers thin, you can keep business logic at Service Objects.
Just create "services" directory at "app", add there some class like "user_searcher.rb".
And call it in the controller, passing all necessary data.
Such technique will help you to isolate business logic and incapsulate it in separate class.
BTW read this article http://blog.codeclimate.com/blog/2012/10/17/7-ways-to-decompose-fat-activerecord-models/
I think, from what I understand of you question, is this code should be placed in the helper classes. If you have dedicated class for this calculation, you can use class attributes to access array to access anywhere in the class or declare them constant, in case they are constant.
I don't think making global is a good practice, just because this is needed in some other function, instead return that variable and pass them as parameter where they are needed.
Is it possible to override the class file location of a framework class via classmap and autoloader? If yes, then how?
Example: I want to override Zend\Form\Fieldset, so that everywhere in the framework where Zend\Form\Fieldset is referenced, I want it to use my own class file instead of the original.
Motivation: When updating the framework, I want to keep my modifications safe from getting overwritten.
Known alternative: Modify the code in the framework.
Disadvantage: Modification gets lost when updating the framework.
writing the same class (FQCN) at another location is generally a bad idea. This causes two classes which are equally named to live in two separate locations. It's a much better idea to create your own Fielset in your own namespace. Say, Application\Form\Fieldset.
You can extend the ZF2 fieldset by your own. Then reference this new fieldset class and its all much more maintainable.
The downside of this method is you don't automatically use the new fieldset class. You have to reference the Application\Form namespace in every form you use. On the other hand, this makes it much more clear to other users of you code what exactly happens: there are no unexpected consequences using ZF2 code.
The only remark I have to make here is, for what do you need another fieldset? If you think you need that for view helpers, that's not true. You can modify the view helper to render fieldsets without modifying the Fieldset form class itself.