Include Task

## Include

### Description

Include another build file into the current project.

since Apache Ant 1.8.0

Note this task heavily relies on the ProjectHelper implementation and doesn't really perform any work of its own. If you have configured Ant to use a ProjectHelper other than Ant's default, this task may or may not work.

On execution it will read another Ant file into the same Project rewriting the included target names and depends lists. This is different from Entity Includes as explained in the Ant FAQ insofar as the target names get prefixed by the included project's name or the as attribute and do not appear as if the file was contained in the including file.

The include task may only be used as a top-level task. This means that it may not be used in a target.

There are two further functional aspects that pertain to this task and that are not possible with entity includes:

- target rewriting
- special properties

#### Target rewriting

Any target in the included file will be renamed to prefix.name where name is the original target's name and prefix is either the value of the as attribute or the name attribute of the project tag of the included file.

The depends attribute of all included targets is rewritten so that all target names are prefixed as well. This makes the included file self-contained.

Note that prefixes nest, so if a build file includes a file with prefix "a" and the included file includes another file with prefix "b", then the targets of that last build file will be prefixed by "a.b.".

`<import>` contribute to the prefix as well, but only if their `as` attribute has been specified.

#### Special Properties

Included files are treated as they are present in the main buildfile. This makes it easy to understand, but it makes it impossible for them to reference files and resources relative to their path. Because of this, for every included file, Ant adds a property that contains the path to the included buildfile. With this path, the included buildfile can keep resources and be able to reference them relative to its position.

So if I include for example a docsbuild.xml file named builddocs, I can get its path as ant.file.builddocs, similarly to the ant.file property of the main buildfile.

Note that "builddocs" is not the filename, but the name attribute present in the included project tag.

If the included file does not have a name attribute, the ant.file.projectname property will not be set.

If you need to know whether the current build file's source has been a file or an URL you can consult the property ant.file.type.projectname (using the same example as above ant.file.type.builddocs) which either have the value "file" or "url".

#### Resolving files against the included file

Suppose your main build file called `including.xml` includes a build file `included.xml`, located anywhere on the file system, and `included.xml` reads a set of properties from `included.properties`:

    <!-- including.xml -->
    <project name="including" basedir="." default="...">
      <include file="${path_to_included}/included.xml"/>
    </project>

    <!-- included.xml -->
    <project name="included" basedir="." default="...">
      <property file="included.properties"/>
    </project>

This snippet however will resolve `included.properties` against the basedir of `including.xml`, because the basedir of `included.xml` is ignored by Ant. The right way to use `included.properties` is:

    <!-- included.xml -->
    <project name="included" basedir="." default="...">
      <dirname property="included.basedir" file="${ant.file.included}"/>
      <property file="${included.basedir}/included.properties"/>
    </project>

As explained above `${ant.file.included}` stores the path of the build script, that defines the project called `included`, (in short it stores the path to `included.xml`) and `<dirname>` takes its directory. This technique also allows `included.xml` to be used as a standalone file (without being included in other project).

The above description only works for included files that actually are included from files and not from URLs. For files included from URLs using resources relative to the included file requires you to use tasks that can work on non-file resources in the first place. To create a relative resource you'd use something like:

      <loadproperties>
        <url baseUrl="${ant.file.included}"
             relativePath="included.properties"/>
      </loadproperties>

### Parameters

Attribute | Description | Required
file | The file to include. If this is a relative file name, the file name will be resolved relative to the including file. Note, this is unlike most other ant file attributes, where relative files are resolved relative to ${basedir}. | Yes or a nested resource collection
optional | If true, do not stop the build if the file does not exist, default is false. | No
as | Specifies the prefix prepended to the target names. If ommitted, the name attribute of the project tag of the included file will be used. | Yes, if the included file's project tag doesn't specify a name attribute.
prefixSeparator | Specifies the separator to be used between the prefix and the target name. Defaults to ".". | No

### Parameters specified as nested elements

#### any resource or resource collection

The specified resources will be included.

### Examples

      <include file="../common-targets.xml"/>

Includes targets from the common-targets.xml file that is in a parent directory.

      <include file="${deploy-platform}.xml"/>

Includes the project defined by the property deploy-platform

      <include>
        <javaresource name="common/targets.xml">
          <classpath location="common.jar"/>
        </javaresource>
      </include>

Includes targets from the targets.xml file that is inside the directory common inside the jar file common.jar.

### How is <import> different from <include>?

The short version: Use import if you intend to override a target, otherwise use include.

When using import the imported targets are available by up to two names. Their "normal" name without any prefix and potentially with a prefixed name (the value of the as attribute or the imported project's name attribute, if any).

When using include the included targets are only available in the prefixed form.

When using import, the imported target's depends attribute remains unchanged, i.e. it uses "normal" names and allows you to override targets in the dependency list.

When using include, the included targets cannot be overridden and their depends attributes are rewritten so that prefixed names are used. This allows writers of the included file to control which target is invoked as part of the dependencies.

It is possible to include the same file more than once by using different prefixes, it is not possible to import the same file more than once.

#### Examples

nested.xml shall be:

    <project>
      <target name="setUp">
        <property name="prop" value="in nested"/>
      </target>

      <target name="echo" depends="setUp">
        <echo>prop has the value ${prop}</echo>
      </target>
    </project>

When using import like in

    <project default="test">
      <target name="setUp">
        <property name="prop" value="in importing"/>
      </target>

      <import file="nested.xml" as="nested"/>

      <target name="test" depends="nested.echo"/>
    </project>

Running the build file will emit:

    setUp:

    nested.echo:
         [echo] prop has the value in importing

    test:

When using include like in

    <project default="test">
      <target name="setUp">
        <property name="prop" value="in importing"/>
      </target>

      <include file="nested.xml" as="nested"/>

      <target name="test" depends="nested.echo"/>
    </project>

Running the target build file will emit:

    nested.setUp:

    nested.echo:
         [echo] prop has the value in nested

    test:

and there won't be any target named "echo" on the including build file.