On The Bike Shed, hosts Joël Quenneville and Stephanie Minn discuss development experiences and challenges at thoughtbot with Ruby, Rails, JavaScript, and whatever else is drawing their attention, admiration, or ire this week.
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Episode 6 - More Code Examples
- Drawing from Chapter 7 - Encapsulation
A weekly podcast about programming, development, and design through the lens of amazing books, chapter-by-chapter.
Encapsulate Record (162)
var organization = { name: "JP Sio", country: "USA" };
becomes ⬇️
class Organization { constructor(data) { this._name = data.name; this._country = data.country; } get name() { return this._name; } set name(arg) { this._name = arg; } get country() { return this._country; } set country(arg) { this._country = arg; } }
- you can hide what is stored and provide methods
- consumer of
class Organization
doesn't need to know / care which is stored and which is calculated - nice getter and setter methods
- makes it easier to refactor -> can hide implementation of internals and update the internals while keeping the same external interface
Encapsulate Collection (170)
class Person { get courses() { return this._courses; } set courses(aList) { this._courses = aList; } }
becomes ⬇️
class Person { get courses() { return this._courses.slice(); } addCourse(aCourse) { /*...*/ } }
slice()
is key here, does not modify the original array - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice- common approach is to provide a getting method for the collection to return a copy
- basically, never mutate the original
Replace Primative with Object (174)
orders.filter(0 => "high" === o.priority || "rush" === o.priority)
becomes ⬇️
orders.filter(o => o.priority.higherThan(new Priority("normal")));
- this goes back to "Primitive Obsession"
- programmers are often hesitant to create their own types and rely only on primitives. i.e. representing a phone number as a string instead of as it's own type
A telephone number may be represented as a string for a while, but later it will need special behavior for formatting, extracting the area code, and the like
- create a new class for that bit of data
- at first, the class does very little. in fact it probably only wraps a primitive
- but now you have a place to put behavior specific to its needs
Inline Function (115) 🥴
Sometimes it's better to not try to split things apart, sometimes it just complicates things.
// before refactor: function getItemPrice(item) { if (itemOnSale(item) == true) { return item.price - 5 } else { return item.price } }; function itemOnSale(product) { if (product.onSale == true) { return true; } else { return false; } }; let original = getItemPrice(sweatshirt); // after refactor: function newGetItemPrice(item) { if (item.onSale == true) { return item.price - 5 } else { return item.price } };
Extract Class (182) 🥴
- Talk through HUGE applicant model (in Ruby)
- Broke this into child objects
- Applicant Health History
- Applicant Habits
- Applicant Lifestyle
- Applicant Method
- Applicant Legal Release
Picks
- JP: None :(
- John: Quad Lock phone mount - bikes
78 episodes