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= macrodef

*Tag:* macrodef

[*__since 1.3__*]

[ivysettings.macrodef]#Defines a new dependency resolver type based upon another.# This definition is very similar to the macrodef feature of Ant for defining macro tasks.

This task eases the process of creating a new dependency resolver, because it avoids writing Java code.

It is generally used in combination with the link:../settings/include{outfilesuffix}[include] feature to help reuse a macro in multiple settings files.

A macro is defined by declaring an existing resolver within it. Then you can use attributes to pass parameters to the newly defined resolver type. Attributes are defined with a name, and optionally a default value, and are used using the following syntax:

[source]
----
@{attributename}
----


== Resolver names

Since you can use the same macro several times it can define several resolvers (in a chain, for instance), the resolver names need to be chosen carefully to avoid name conflicts (each resolver must have a unique name).

Here is how Ivy deals with the names of the resolvers defined in a macro:


    * if there is no name attribute on a resolver in the macrodef, then Ivy will use the name given when using the macro. This is what usually should be done for the main resolver defined in the macro

    * if there is a name attribute on a resolver in the macrodef, but this name doesn't contain a `@{name}` inside, then Ivy will use the provided name prefixed with the name of the macro separated by a dash

    * if there is a name attribute on a resolver in the macrodef, and this name contains `@{name}` somewhere, then Ivy will use this name, and replace `@{name}` with the name provided when using the macro.


Example:

[source, xml]
----

<ivysettings>
  <macrodef name="mymacro">
    <chain>
      <ibiblio name="ex1"/>
      <ibiblio name="ex2.@{name}" m2compatible="true"/>
    </chain>
  </macrodef>

  <resolvers>
    <mymacro name="default"/>
    <mymacro name="other"/>
   </resolvers>
</ivysettings>

----

This is equivalent to:

[source, xml]
----

<ivysettings>
  <resolvers>
    <chain name="default">
      <ibiblio name="default-ex1"/>
      <ibiblio name="ex2.default" m2compatible="true"/>
    </chain>
    <chain name="other">
      <ibiblio name="other-ex1"/>
      <ibiblio name="ex2.other" m2compatible="true"/>
    </chain>
   </resolvers>
</ivysettings>

----


== Attributes


[options="header",cols="15%,50%,35%"]
|=======
|Attribute|Description|Required
|name|name of the resolver type created|Yes
|=======


== Child elements


[options="header"]
|=======
|Element|Description|Cardinality
|link:../settings/macrodef/attribute{outfilesuffix}[attribute]|defines an attribute for the macro resolver|0..n
|any resolver|defines the base resolver upon which this macro is defined|1
|=======


== Examples

Defining a simple macro:

[source, xml]
----

  <macrodef name="mymacro">
    <attribute name="mymainrep"/>
      <filesystem name="fs1">
        <ivy pattern="@{mymainrep}/[organisation]/[module]/[type]s/[artifact]-[revision].[ext]"/>
        <artifact pattern="@{mymainrep}/[organisation]/[module]/[type]s/[artifact]-[revision].[ext]"/>
      </filesystem>
  </macrodef>

----

Using it:

[source, xml]
----

  <resolvers>
    <mymacro name="default" mymainrep="path/to/myrep"/>
  </resolvers>

----


'''

A complete example:

[source, xml]
----

<ivysettings>
  <macrodef name="mymacro">
    <attribute name="mymainrep"/>
    <attribute name="mysecondrep"/>
    <attribute name="myseconddirlayout" default="[organisation]/[module]/[type]s"/>
    <chain>
      <filesystem name="fs1">
        <ivy pattern="@{mymainrep}/[organisation]/[module]/[type]s/[artifact]-[revision].[ext]"/>
        <artifact pattern="@{mymainrep}/[organisation]/[module]/[type]s/[artifact]-[revision].[ext]"/>
      </filesystem>
      <filesystem name="fs2" latest="latest-time">
        <ivy pattern="@{mysecondrep}/@{myseconddirlayout}/ivy-[revision].xml"/>
        <artifact pattern="@{mysecondrep}/@{myseconddirlayout}/[artifact]-[revision].[ext]"/>
      </filesystem>
    </chain>
  </macrodef>

  <resolvers>
    <mymacro name="default" mymainrep="path/to/myrep" mysecondrep="path/to/secondrep"/>
    <mymacro name="other"
       mymainrep="path/to/myrep"
       mysecondrep="path/to/secondrep"
       myseconddirlayout="[module]/[type]s"/>
   </resolvers>
</ivysettings>

----