intellij-sdk-code-samples/tutorials/live_templates/new_macros.md

---
title: Creating New Functions for Live Templates
---
<!-- Copyright 2000-2020 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file. -->

The [Predefined Functions](https://www.jetbrains.com/help/idea/template-variables.html?s=quick#predefined_functions) are the building blocks for creating [Parameterized Templates and Surround Templates](https://www.jetbrains.com/help/idea/using-live-templates.html?s=quick#live_templates_types).
However, sometimes the Predefined Functions are not enough.

This tutorial illustrates how to add custom functions to an IntelliJ Platform plugin and make them available for use by Live Templates. 
As an example, a function is created to convert a selection to Title Case.
Refer to the SDK code sample [`live_templates`](https://github.com/JetBrains/intellij-sdk-docs/tree/master/code_samples/live_templates).

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{:toc}

## Implementing a New Function
Under the hood, the predefined functions for Live Templates are called _macros_.
A new custom function for Live Templates is implemented in `TitleCaseMacro`, which extends [`MacroBase`](upsource:///platform/lang-impl/src/com/intellij/codeInsight/template/macro/MacroBase.java).
Three `TitleCaseMacro` methods are of particular interest:
* The `TitleCaseMacro()` constructor passes the name and description of the macro to the parent constructor.
* The `isAcceptableInContext()` method tests whether the macro is available in the current context. 
  The test relies on the [`MarkdownContext`](template_support.md#implement-templatecontexttype) object previously defined in the `live_templates` plugin.
* The `calculateResult()` method gets invoked when the titleCase function is used in a Live Template.
  The text to be capitalized is retrieved from the Live Template and converted to Title Case.

```java
{% include /code_samples/live_templates/src/main/java/org/intellij/sdk/liveTemplates/TitleCaseMacro.java%}
```

## Adding a Live Template
Using the procedures previously discussed for [Template Creation](template_support.md#template-creation) and [Export the Live Template](template_support.md#export-the-live-template), add a Live Template to the [Markdown.xml](https://github.com/JetBrains/intellij-sdk-docs/tree/master/code_samples/live_templates/src/main/resources/liveTemplates) file for the plugin.
The XML representation of an example Live Template using the new `titleCase` function is listed below.

There is only one variable, `TITLE`.
The expression for `TITLE` evaluates to the `titleCase` function provided by the plugin.
The argument to the `titleCase` function is `SELECTION`, which tells the IntelliJ Platform to operate on the current selection.

```xml
<template name="mc"
        value="$TITLE$"
        description="SDK: Convert to title case"
        toReformat="true"
        toShortenFQNames="false">
  <variable name="TITLE" expression="titleCase(SELECTION)" defaultValue="the quick brown fox" alwaysStopAt="true" />
  <context>
    <option name="MARKDOWN" value="true" />
  </context>
</template>
```
 
## Register Extension Point
Using the `com.intellij.liveTemplateMacro` extension point, register the implementation with the IntelliJ Platform.

```xml
  <extensions defaultExtensionNs="com.intellij">
    <liveTemplateMacro implementation="org.intellij.sdk.liveTemplates.TitleCaseMacro"/>
  </extensions>
```

## Check Plugin
Now verify the plugin is working correctly. 
* Run the plugin in a Development Instance.
* Create a new file `testing.md` and enter several words in lower case.
* Highlight the text and enter <kbd>⌥⌘J</kbd> to open the Select Template popup.
  Confirm that the _SDK: Convert to title case_ is available in the popup, and select it.

![Convert to title case](img/invoke_titleCase.png){:width="700px"}

Test that the Live Template works by entering <kbd>m</kbd> or <kbd>return</kbd>.
The text will change to have each word capitalized: 

![Converted to title case](img/applied_titleCase.png){:width="700px"}