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Code completion

Last modified: 10 December 2021

Configure: Settings/Preferences | Editor | General | Code Completion

For automatic completion enable the Show suggestions as you type option

Basic completion: Ctrl+Space

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/2021.2/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

  • 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

  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:

Complete tag names

Import a taglib declaration

Insert a tag declared in a taglib

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 Icons 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.

Preselect first completion element

Choose this option if you want to preselect the first item in the suggestions list.

Completion tips and tricks

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 Definitions 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.

Use machine-learning-assisted code completion

You can utilize machine learning models to rank most suitable items higher in the suggestions list.

To do so, press Ctrl+Alt+S to open the IDE settings and select Editor | General | Code Completion, and then enable the Sort completion suggestions based on machine learning option under Machine Learning-Assisted Completion.

ML-assisted completion settings

The Machine Learning ranking Up and Machine Learning ranking Down arrow icons indicate whether the relevance of a suggestion is increasing or decreasing and therefore the suggestion has moved up or down the list. The ML relevant proposal icon indicates the most suitable suggestion.

ML-assisted completion

The ML completion mechanism doesn't add any new elements but orders the elements retrieved from the script or runtime. Data are not exposed anywhere; they are collected locally.

    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.

    See also

    Getting Started