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>Subpackages</A
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><P
>Sometimes a package consists of several archive files that are closely
related. It is now possible to express dependencies between these
archives by splitting the package into several parts called subpackages.
For example, package p consists of a base archive p_base.cma, and two
extensions p_ext1.cma and p_ext2.cma that both require the base archive
but are independent of each other. This META file expresses this
dependency directly:
<PRE
CLASS="PROGRAMLISTING"
># META file of package p:
requires = "p.base"
package "base" (
archive(byte) = "p_base.cma"
)
package "ext1" (
requires = "p.base"
archive(byte) = "p_ext1.cma"
)
package "ext2" (
requires = "p.base"
archive(byte) = "p_ext2.cma"
)</PRE
>
If installed as package "p", this definition actually defines four
logical packages: "p" (the main package), "p.base", "p.ext1", and
"p.ext2" (the subpackages). These four entities only share the META
file in which they are declared, and the directory where the archive
files are stored, but all other properties can be individually set
for each package. This also means that all package dependencies
must explicitly added by "requires" variables, as there are no
implied dependencies. In this example, the main package and "p.ext1"
and "p.ext2" are all dependent on "p.base".</P
><P
>The users of this installation can refer to all four packages. This
means that
<PRE
CLASS="PROGRAMLISTING"
>ocamlfind ocamlc -package p -linkpkg ...</PRE
>
links only p_base.cma into the final program, while
<PRE
CLASS="PROGRAMLISTING"
>ocamlfind ocamlc -package p.ext1 -linkpkg ...</PRE
>
selects both p_base.cma and p_ext1.cma.</P
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