DH_SAMEVERSIONDEP(1)					User Contributed Perl Documentation				      DH_SAMEVERSIONDEP(1)

NAME

       dh_sameversiondep - generate versioned dependency based on the versioned dependencies of the reference package.

SYNOPSIS

       dh_sameversiondep [debhelper options]

DESCRIPTION

       dh_sameversiondep is a helper tool which is able to generate a dependency that is versioned the same way as a dependency (coming from the
       same source) of another reference package.  dh_sameversiondep scans debian/control for the specially formatted substvar (see
       "sameVersionDep substvar SPECIFICATION" section below), determines its value and writes it to debian/package.substvars file.

       The most common use case for dh_sameversiondep tool is to keep your liba-dev package dependency on the external libb-dev package as tight
       as your liba package depends on the respective external libb package (see "EXAMPLE" section for more information about this use case).

       dh_sameversiondep works as follows:

       o   Searches for the sameVersionDep substvar in the Depends, Recommends, Suggests, Enhances and Pre-Depends fields of the requested
	   packages. When one is found, it is parsed and the dependency package name, reference package name and dependency type (either Depends
	   or Recommends etc.) are determined.

       o   All dependencies of the requested type are collected for the dependency package based on the dpkg-query --status output.

       o   All dependencies of the requested type are collected for the reference package either from debian/control (substvars are expanded) or
	   from dpkg-query --status output if the package was not found in debian/control.

       o   Both collections are intersected leaving only common packages in both collections.

       o   Common package list is filtered by leaving only those which come from the same source as dependency package.

       o   Whatever packages are left (most likely only one), their names are replaced with dependency package name preserving all versioning
	   information. This result is written to debian/package.substvars file as a value of the sameVersionDep substvar being processed.

       dh_sameversiondep is very strict about errors. If either dependency package or the reference package cannot be found or the resulting
       dependency set is empty, it will fail with an error.

       dh_sameversiondep MUST be run before dh_gencontrol. However, it is recommended to run dh_sameversiondep after dh_shlibdeps.

sameVersionDep substvar SPECIFICATION
       sameVersionDep substvar can appear in either Depends, Recommends, Suggests, Enhances or Pre-Depends field of any binary package. The field,
       which the substvar appears in, becomes the default dependency type for that substvar.  sameVersionDep should be formatted as follows
       (everything is case sensitive):

       ${sameVersionDep:dependency[[:reference]-dependency type]}

       dependency (mandatory)
	   The name of the package which you want to add as a dependency.

       reference (optional)
	   The name of the package which dependencies are to be intersected with the dependencies of the dependency package. Defaults to the first
	   package in debian/control if ommited.

       dependency type (optional)
	   Can be either Depends, Recommends, Suggests, Enhances or Pre-Depends. Defaults to the name of the field which the substvar was found
	   in. Specifies which type of dependencies to consider when analyzing dependency package and reference package.

EXAMPLE

       Assume we have the following in debian/control:

	   Package: liba
	   Depends: libc (>= 0.1), depa, depb, depc

	   Package: libb
	   Depends: libd (>= 0.2), depd, depe, depf

	   Package: libab-dev
	   Depends: ${sameVersionDep:libc-dev}, ${sameVersionDep:libd-dev:libb}

       Assumming that libc and libc-dev (both from the same source), as well as libd and libd-dev (both from the same source) are installed, the
       value of "sameVersionDep:libc-dev" will be libc-dev (>= 0.1) and the value of "sameVersionDep:libd-dev:libb" will be libd-dev (>= 0.2).

       "sameVersionDep:libc-dev" could also be written as "sameVersionDep:libc-dev:liba-Depends" and "sameVersionDep:libd-dev:libb" as
       "sameVersionDep:libd-dev:libb-Depends" but it is not necessary because defaults are sufficient.

SEE ALSO

       debhelper(7)

AUTHOR

       Modestas Vainius <modax@debian.org>

perl v5.14.2							    2012-08-05						      DH_SAMEVERSIONDEP(1)