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Code completion

Last modified: 16 January 2023

Configure: Settings | Editor | General | Code Completion

For automatic completion, enable the Show suggestions as you type option

Basic completion: Ctrl+Space

To reject all suggestions, press Escape.

This section covers various techniques of context-aware code completion that allow you to speed up your coding process.

Basic completion

Basic code completion helps you complete the names of classes, methods, and keywords within the visibility scope.

When you invoke code completion, RubyMine analyses the context and suggests the choices that are reachable from the current caret position (suggestions also include Live templates).

tip

Code completion is available for custom file types. However, RubyMine does not recognize the structure of such files, and suggests options regardless of whether they are appropriate in the current context.

tip

Basic completion is also available for a non-English keyboard layout.

Invoke basic completion

  1. Start typing a name.

  2. Press Ctrl+Space or choose Code | Code Completion | Basic from the main menu.

    Basic completion

  3. If necessary, press Ctrl+Space for the second time (or press Ctrl+Alt+Space).

    The completion popup shows all declared names. In this case, RubyMine suggests text-based results regardless of whether they are appropriate in the current context.

    Declared names completion

Hippie completion

Hippie completion is a completion engine that analyses your text in the visible scope and generates suggestions from the current context. It helps you complete any word from any of the currently opened files.

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.

    https://resources.jetbrains.com/help/img/idea/2022.3/rm_expandWord.png
    Gif

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

Postfix code completion

Postfix code completion helps you reduce backward caret jumps as you write code. You can transform an already-typed expression to a different one based on a postfix you type after the dot, the type of expression, and its context.

Enable and configure postfix completion

  • In the Settings dialog (Ctrl+Alt+S), open 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

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

    Postfix completion

  2. (Optional step) If required, select an expression that will be used as a condition:

    Postfix completion expression

  3. Press Enter:

    Postfix completion result

You can disable certain postfix completion templates in the Editor | General | Postfix Completion page of the IDE settings Ctrl+Alt+S.

You can select Tab,Space, or Enter to expand postfix templates.

You can edit the predefined postfix templates, for example, to replace a long key with a shorter one, or to expand the list of applicable expression types.

tip

Postfix completion options are shown as part of the basic completion suggestions list. To see a full list of postfix completions applicable in the current context, press Ctrl+J.

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 (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, $EXPR$ =!null.

Completion of tags and attributes

RubyMine automatically completes names and values of tags and attributes in many file types:

Machine-learning-assisted code completion

RubyMine allows you to prioritize completion suggestions based on choices that other users made in similar situations.

The ML completion mechanism doesn't add any new elements but orders the elements retrieved from code. Data is not exposed anywhere; it is collected locally.

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.

    ML-assisted completion settings

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 Machine Learning ranking Up and Machine Learning ranking Down 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 ML relevant proposal icon to indicate the most suitable suggestion on the list.

    The suggestion list will look as follows with the icons marking reordered and the most relevant items.

    ML-assisted completion

Configure code completion settings

To configure code completion options, go to the Editor | General | Code Completion page of the IDE settings Ctrl+Alt+S.

You can choose the following settings:

Item

Description

Match case

Select if you want letter case to be taken into account for completion suggestions. Choose whether you want to match case for the first letter or for all letters.

Automatically insert single suggestions for

Select if you want to automatically complete code if there's just one suggestion for basic and/or smart type-matching completion.

Sort suggestions alphabetically

Select if you want to sort items in the suggestions list in the alphabetical order instead of sorting them by relevance.

You can change this behavior at any time by clicking App actions more in the suggestion list and toggling the Sort by Name option.

Show suggestions as you type

Select if you want the suggestions list to be invoked automatically, without having to call completion explicitly. This option is enabled by default.

Insert selected suggestion by pressing space, dot, or other context-dependent keys

Select if you want to insert the selected suggestion by typing certain keys that depend on the language, your context, and so on.

Show the documentation popup in

Select to automatically show a popup for each item in the suggestions list with the documentation for the class, method, or field currently highlighted in the lookup list.

In the field to the right, specify the delay (in milliseconds), after which the popup should appear.

Insert parentheses automatically when applicable

If this option is enabled, RubyMine automatically inserts a pair of opening and closing parentheses when you complete a function/method.

Clear the checkbox to suppress inserting parentheses automatically.

If you use an opening parentheses ( instead of Enter to apply the selected item from a completion list, parentheses will be inserted automatically no matter whether the option is turned on or off.

To use an opening parentheses ( instead of Enter to apply the selected item from a completion list, open the Settings dialog (Ctrl+Alt+S), go to Editor | General | Code Completion, and select the Insert selected suggestion by pressing space, dot, or other context-dependent keys checkbox.

See Use specific keys to insert suggestions for details.

Completion tips and tricks

Open completion settings from the completion popup

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

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

    Opening 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 . RubyMine will show suggestions that include the characters you've entered in any positions.

    This makes the use of wildcards unnecessary:

    code completion wildcard

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

    code completion wildcard

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.

note

While this setting helps you save time, turning it on may result in items being inserted accidentally.

View reference

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

    completion quick definition

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

    Quick documentation

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.

Troubleshooting

If code completion doesn't work, this may be due to one of the following reasons:

  • The Power Save Mode is on (File | Power Save Mode). Turning it on minimizes power consumption of your laptop by eliminating the background operations, including error highlighting, on-the-fly inspections, and code completion.

  • An SDK is not configured for your project.

  • Your file doesn't reside in a content root , so it doesn't get the required class definitions and resources needed for code completion.

  • A file containing classes and functions that you want to appear in completion suggestions list is marked as a plain text file.

  • External libraries that contain functions that you want to appear in the completion suggestions list are not added as dependencies or global libraries.

  • Code completion popup might not appear automatically if it takes too long to gather the completion options. For example, if the computer is busy with another task. In this case, you may still activate the completion popup manually via Ctrl+Space hotkey.

See also

Getting Started