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template.md

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Macro
template ';' NAME [ ';' template ]+
Expand the entries of a merged and decorated Parameters object using a template that can refer to the key and attributes

The template macro is intended to make it very simple to generate new information based on a Parameters. Parameters are the Bnd workhorse to store information. The macro takes the following arguments:

macro name  The name of the macro (not the value)
template+   the templates (these are  joined with the ';' as separator)

The template is expanded for each entry of the Parameters. They key can be referred by ${@} and the attributes can be referred by ${@<name>}, where the name is the name of the attribute. All entries are then joined with a comma (,) as separator.

For example, the following example shows how to extract and attribute as a list:

bnd shell
> parameters = key;attr=1, key;attr="2"
> ${template;parameters;${@attr}}
1,2

The template macro takes the NAME of the macro that contains the value. I.e. it does not take the expanded value as argument. The reason is that the referred macro gets merged and decorated. Merge takes all properties that start with the given name.

> parameters = key;attr=1, key;attr="2"
> parameters.extra = KEY;attr=3, KEY;attr="4"
> ${template;parameters;${@attr}}
1,2,3,4

Decorate means that the property with the same name but with a + at the end will be matched with the value. In this property the key is a glob. It is matched against the key from the original merged properties. Any matching properties get the attributes from the decorator.

> parameters = a;attr=1, b;attr="2"
> parameters.extra = c;attr=3, d;attr="4"
> parameters+ = (c|d);attr=X
> ${template;parameters;${@attr}}
1,2,X,X

The macro accepts any number of arguments after the macro name. These values are joined with a semi-colon as separator. The reason is that then the ; in the templates do not have to be escaped:

bnd shell
> parameters = a;attr=1, b;attr="2"
> ${template;parameters;${@};key=${@};${@}=${@attr}}
a;a=1,b;b=2