Code completion

Invoke basic completion

By default, GoLand displays the code completion popup automatically as you type. Alternatively, you can press Ctrl+Space or select Code | Code Completion | Basic from the main menu.

Invoke completion for functions

• To view and complete functions that are suitable for a value of the certain type, hold Ctrl and press Space twice.

  For example, you have the t variable of the string type. When you type t., hold Ctrl and press Space twice, you see a list of functions that accept the string type as the first argument.

  

Invoke type-matching completion

• Smart type-matching code completion filters the suggestions list and shows only the types applicable to the current context. To invoke type-matching completion, start typing your code and press Ctrl+Shift+Space. Alternatively, select Code | Code Completion | Type-Matching from the main menu. The following animation shows the difference between basic and type-matching completion.

Expand a string at caret to an existing word

1. Type the initial string and do one of the following:

   • Press Alt+/ or choose Code | Code Completion | Cyclic Expand Word to search for matching words before the caret.

   • Press Alt+Shift+/ or choose Code | Code Completion | Cyclic Expand Word (Backward) to search for matching words after the caret and in other open files.

   The first suggested value appears, and the prototype is highlighted in the source code.

2. Accept the suggestion, or hold the Alt key and keep pressing / until the desired word is found.

Enable and configure postfix completion

• Go to Settings / Preferences | Editor | General | Postfix Completion and select the Enable postfix completion checkbox.

• Select Tab, Space, or Enter to be used for expanding postfix templates.

• Enable/disable a particular postfix template for the selected language.

Transform a statement with a postfix

Type an expression and then type a postfix after a dot, for example, .if:

The initial expression gets wrapped with an if statement:

Create custom postfix templates

1. Press Ctrl+Alt+S to open the IDE settings and select Editor | General | Postfix Completion.

2. Click the Add button () on the toolbar.

3. Specify Key that is a combination of symbols that will invoke the template.

4. Select which expression types the new template will be applicable to, and type the target expression in the following format: $EXPR$ <target_expression>, for example, $EXPR$ != nil.

   Inside your template, you can use two predefined variables, $EXPR$ and $END$:

   • $EXPR$ captures the expression before the dot.

   • $END$ defines the position of the cursor after the template is expanded.

   The Apply to the topmost expression checkbox applies your template to the entire expression ignoring the scope. So you do not need to select the scope for the template each time.

   

Enable ML completion

1. Press Ctrl+Alt+S to open the IDE settings and select Editor | General | Code Completion.

2. Under Machine Learning-Assisted Completion, enable the Sort completion suggestions based on machine learning option, and select the languages for which you want to use ML completion.

   

Enable relevance markers

1. Press Ctrl+Alt+S to open the IDE settings and select Editor | General | Code Completion.

2. Enable the following options:

   • Mark position changes in the completion popup: use the and icons to indicate whether the relevance of a suggestion is increasing or decreasing and therefore the suggestion has moved up or down the suggestion list.

   • Mark the most relevant item in the completion popup: use the icon to indicate the most suitable suggestion on the list.

   

Configure completion options

1. Press Ctrl+Alt+S to open the IDE settings and select Editor | General | Code Completion.

2. • To automatically display the suggestions list, select the Show suggestions as you type checkbox. If the checkbox is cleared, you have to call code completion explicitly by pressing Ctrl+Space for basic completion or Ctrl+Shift+Space for type-matching completion.

     You can also choose to automatically insert suggestions when there's just one option: select the completion type under Automatically insert single suggestions for.

   • To sort suggestions in the alphabetical order, instead of sorting them by relevance, select the Sort suggestions alphabetically checkbox.

     You can also toggle these modes by clicking or respectively in the lower-right corner of the suggestions list.

   • If you want the documentation popup to be displayed automatically for each item in the suggestions list as you scroll it, select the Show documentation popup in option. In the field to the right, specify the delay (in milliseconds), after which the popup should appear.

Open completion settings from the completion popup

You can quickly access code completion settings right from the completion popup.

• Click the icon in the completion popup and select Code Completion Settings.

  

After that, the Editor | General | Code Completion page of the IDE settings Ctrl+Alt+S opens.

Narrow down the suggestions list

• You can narrow down the suggestions list by typing any part of a word (even characters from somewhere in the middle) or invoking code completion after a dot separator . GoLand will show suggestions that include the characters you've entered in any positions.

  This makes the use of wildcards unnecessary:

  

  In case of CamelCase or snake_case names, type the initial letters only. GoLand automatically recognizes and matches the initial letters.

Accept a suggestion

You can accept a suggestion from the list in one of the following ways:

• Press Enter or double-click a list item to insert it to the left of the caret.

• Press Tab to replace the characters to the right from the caret.

• Use Ctrl+Shift+Enter to make the current code construct syntactically correct (balance parentheses, add missing braces and semicolons, and so on).

You can also use specific keys to insert the selected completion suggestion: go to the Editor | General | Code Completion page of the IDE settings Ctrl+Alt+S and select the Insert selected suggestion by pressing space, dot, or other context-dependent keys option. These keys depend on the language, your context, and so on.

View reference

• You can use the Quick Definition view by pressing Ctrl+Shift+I when you select an entry in the suggestions list:

  

• You can use the Quick Information view by pressing Ctrl+Q when you select an entry in the suggestions list:

View code hierarchy

You can view code hierarchy when you've selected an entry from the suggestions list:

• Ctrl+H - view type hierarchy

• Ctrl+Shift+H - view method hierarchy.

Fill struct fields

When you create a new struct, you can automatically generate field names for it. This action works for generic structs.

The IDE ignores auto-generated protocol buffer fields that start with XXX_ when you invoke the Fill all fields intention action. These fields are shown only after you invoke completion for a second time.

1. Start typing the struct name, select it from the completion list.

2. Place a caret between braces of a struct.

3. Press Ctrl+Space. Alternatively, press Alt+Enter.

4. Select between the following options:

   • Fill all fields: generates values for all the fields that belong to the current struct.

   • Fill all fields recursively: generates values for all the fields that belong to the current struct type and all the pointers to other struct types recursively.

   • Fill fields: displays the Select Fields dialog where you can select the fields that you want to add. Select Recursively to parse fields from all the related structs. Clear the Enforce multiline checkbox to display all fields on a single line. In the Select Fields dialog, press Ctrl and click the fields that you want to add.

5. Click OK.

   

Format date and time

• The time package uses predefined layouts that you can use in Time.Format and time.Parse. The reference time used in the layouts is the specific time: Mon Jan 2 15:04:05 MST 2006. It means that to define your own format, you need to write down what the reference time would look like formatted your way.

  In GoLand, when you press Ctrl+Space, you will see placeholders for time and data elements from ISO-8601. Code completion also suggests standard time layouts outside of the string literal.