Completion Tips & Tricks

Know everything there is to know about Code Completion.

2019-11-27

Code completion is one of the greatest benefits of using an IDE: it reduces the number of things that you need to memorize and helps avoid typos and other common mistakes. It is useful for both professional developers who can write clean code faster, and for beginners who get easier ways of learning programming languages.

In this playlist we're going to have a look at the many code completion features in GoLand, and how to effectively use them.

Basic Code Completion

Code completion out-of-the-box that helps you get the job done.

Basic completion provides a list of all symbols available at the current caret position.

The list will include the usual mix of type, interface, and method names, keywords, and also Live Templates.

Symbols from not-yet-imported packages are also offered, with autoimport on-the-fly when you select them.

Basic completion pops up as you start typing code and GoLand recognizes an opportunity to complete something for you, but you can invoke it anytime by pressing ⌃␣ (macOS) / Ctrl+Space (Windows/Linux).

Basic Code Completion is also available for non-English symbols.

Smart Code Completion

Let code completion help you out in GoLand.

Smart code completion narrows down the matches to quickly give you a list of useful values.

Smart Code Completion gives you a list of the most relevant symbols that are applicable in the current context.

Press ⌃⇧␣ (macOS) / Ctrl+Shift+Space (Windows/Linux).

Cyclic Expand Word - Hippie Completion

Complete any word any from the current open files.

Cyclic Expand Word helps you complete any word any from the current open files

It's a type of code completion that analyzes your code in the visible scope, helps you to complete any word from any of the currently opened files, and provides you with suggestions from the current context, which can save you plenty of time when, for example, you are working on boilerplate code.

Press ⌥⏎ (macOS) / Alt+Enter (Windows/Linux) to search for matching words before the caret or choose Code | Completion | Cyclic Expand Word.

Press ⌥⇧/ (macOS) / Shift+Alt+/ (Windows/Linux) for searching words after the caret or choose Code | Completion | Cyclic Expand Word (Backward).

Hold the ⌥ (macOS) / Alt (Windows/Linux) key down and keep pressing / until you get to the word you need.

Method-like Completion for Functions

Completion for searching for functions that accept parameters of a certain type.

Method-like completion for functions allows you to search for functions based on their first parameter.

Imagine you are new to Go and want to split a string.

You know that there must be a function for that, most likely it's called Split and accepts a string as the first argument, but you don't know the exact name of the function and its package.

Here's where method-like completion comes in handy, offering you a list of all suitable functions, automatically importing it upon selection.

Hold down the Ctrl key and press Space twice.

Postfix Completion

Transform an expression into another one.

Postfix Completion lets you transform an expression into another one, based on the postfix you specify after the dot, the current context, and the expression type.

For example, you can turn a bool expression into an if statement, or create a pointer to an expression. If anything goes not as planned, everything can be reverted via simple ⌘Z (macOS) / Ctrl+Z (Windows/Linux).

Open the Postfix Completion page via Settings/Preferences | Editor | General to see the complete list of supported templates.

Postfix Completion

Basic Completion

Ctrl+J

Postfix Completion

You can change the names of all Postfix Completions in the Settings/Preferences dialog.
In the same dialog, you can also disable the templates you don't need, or even turn off Postfix Completion completely.

Complete Current Statement

Add trailing commas or braces and move the cursor to the right place with a single keystroke.

GoLand can complete statements and add required trailing commas for any composite literals (like struct, slice, etc.), and even place caret in a position where you can just start typing the next statement.

After typing parentheses, trigger the Complete Current Statement action, ⌃⇧⏎ (macOS) / Ctrl+Shift+Enter (Windows/Linux), to add curly braces and move ethe cursor down to the beginning of the next row.

Partial Match Completion

Complete anything by typing just parts of the identifier.

GoLand provides completion suggestions when you typed only a part of a word (any part, even characters from somewhere in the middle).

Also, case-insensitive CamelHump completion is supported, so you can just type the capital letters along with a number of subsequent characters. For example, type ReWrCl to get io.ReadWriteCloser.

Works automatically, you don't have to do anything.

View Parameter Info

Quickly see function arguments and argument types.

Have a function with lots of arguments? Or a struct with many fields? Parameter Info gives just the basics without using lots of real estate.

Press ⌘P (macOS) / Ctrl+P (Windows/Linux) to invoke this feature.

With your cursor in the parentheses, invoke Parameter Info. You get a tiny popup with the positional and keyword arguments, along with any default values. Bold is used to mark the current spot in the parameter list that your cursor is at.

You can invoke this before you type any parameters, after you've typed a few, or later if you come back to make a change.

Completion for non-imported Go Modules

Import a module in to your project.

GoLand provides code completion suggestions for all modules in the modules cache as you type.

Even if a module has never been imported and used in your project, GoLand is still aware of it and will take care of you.

Completion will work automatically as you start typing a package name.

Code completion in Evaluate Expression, Watches or Conditional Breakpoints

The debugger also has extensive code completion capabilities.

You got it right, debugger also has code completion! GoLand provides suggestions list when you evaluate the state of your application in a debugging session.

As you start typing in the Evaluate Expression, Watches or Conditional Breakpoints dialogs, code completion will appear immediately.

Code completion in Run Configurations

Run configurations also have code completion capabilities.

When you're editing Run/Debug Configurations, code completion will automatically appear to help you, for example, type a package name.

As you start typing in the Package, File, or Directory inputs, the IDE will assist you.

Completion with the Tab key

A small, but handy feature that makes it a little easier to complete symbol names.

This will overwrite the identifier at the caret, making it easy to quickly replace identifiers in code.

Use the ⇥ (macOS) / Tab (Windows/Linux) instead of ⏎ (macOS) / Enter (Windows/Linux) to accept a suggestion from list.

Code Completion in Language Injections

See how to use code completion inside strings and other places.

GoLand provides code completion and analysis in injected strings for SQL and databases statements, JavaScript, CSS, HTML, XML, and RegExp, etc.

Place the cursor within the literal (between the quotation marks) and press ⌃⏎ (macOS) / Ctrl+Enter (Windows/Linux), select Inject language or reference, choose which one of supported injection language you want to use and start typing, auto-completion will appear instantly.

Exclude Items from Auto-imports and Completion

Exclude certain paths from auto-import and completion.

Exclude undesired imports from being automatically imported or added to completion list.

In Settings/Preferences | Go | Imports you can add as many as you want import statements that will be excluded from code completion and auto-import.