Naming things (= variables, properties, functions, methods, classes) correctly and in an understandable way is an extremely important part of writing clean code.
Be Descriptive
Names have one simple purpose: They should describe what’s stored in a variable or property or what a function or method does. Or what kind of object will be created when instantiating a class.
If you keep that in mind, coming up with good names should actually be straightforward - though coming up with the best name for a given variable/ property/ function/ … will of course still require some practice and often multiple iterations. That’s normal though - clean code is written by iterating and improving code over time!
Naming Rules
Variables & Properties
Variables and properties hold data - numbers, text (strings), boolean values, objects, lists, arrays, maps etc.
Hence the name should imply which kind of data is being stored.
Therefore, variables and properties should typically receive a noun as a name. For example: user, product, customer, database, transaction etc.
Alternatively, you could also use a short phrase with an adjective - typically for storing boolean values. For example: isValid, didAuthenticate, isLoggedIn, emailExists etc.
Typically, if you can be more specific, you should be more specific.
For example, prefer customer over user if the code at hand is doing customer-specific operations with that data. This makes your code easier to read and understand.
Functions & Methods
Functions and methods can be called to then execute some code. That means that they perform tasks and operations.
Therefore, functions and methods should typically receive a verb as a name. For example: login(), createUser(), database.insert(), log() etc.
Alternatively, functions and methods can also be used to primarily produce values - then, especially when producing booleans
you could also go for short phrases with adjectives. For example: isValid(...), isEmail(...), isEmpty(...) etc.
You should try to avoid names like email(), user() etc. These names sound like properties. Prefer getEmail() etc. instead.
As with variables and properties, if you can be more specific, it typically makes sense to use such more specific names. For example: createUser() instead of just create().
Classes
Classes are used to create objects (unless it’s a static class).
Hence the class name should describe the kind of object it will create. Even if it’s a static class (i.e. it won’t be instantiated), you will still use it as some kind of container for various pieces of data and/ or functionality - so you should then describe that container.
Good class names - just like good variable and property names - are therefore nouns.
For example: User, Product,RootAdministrator, Transaction, Payment etc.
Avoid Generic Names
In most situations, you should avoid generic names like handle(), process(), data, item etc.
There can always be situations where it makes sense but typically, you should either make these names more specific (e.g. processTransaction()) or go for a different kind of name (e.g. product instead of item).
Be Consistent
An important part of using proper names is consistency.
If you used fetchUsers() in one part of your code, you should also use fetchProducts() - and not getProducts() - in another part of that same code.
Generally, it doesn’t matter if you prefer fetch...(), get...(), retrieve...() or any
other term but you should be consistent!