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| author |   Michał Górny <mgorny@gentoo.org> | 2018-01-13 00:23:30 +0100 |
|---|---|---|
| committer |   Göktürk Yüksek <gokturk@gentoo.org> | 2018-02-13 11:43:32 -0500 |
| commit | 7266aee16fa73086a1d9553ab9129013d83a4761 (patch) | |
| tree | 7c8b956ce242a3270eb7c0575b37c4b1a6e91806 /general-concepts/virtuals | |
| parent | general-concepts/virtuals: Explain how keywording works on virtuals (diff) | |
| download | devmanual-7266aee16fa73086a1d9553ab9129013d83a4761.tar.gz devmanual-7266aee16fa73086a1d9553ab9129013d83a4761.tar.bz2 devmanual-7266aee16fa73086a1d9553ab9129013d83a4761.zip | |
general-concepts/virtuals: Tips on virtual and subslots
Diffstat (limited to 'general-concepts/virtuals')
| -rw-r--r-- | general-concepts/virtuals/text.xml | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/general-concepts/virtuals/text.xml b/general-concepts/virtuals/text.xml index 4809394..ff4995a 100644 --- a/general-concepts/virtuals/text.xml +++ b/general-concepts/virtuals/text.xml @@ -70,5 +70,85 @@ RDEPEND="|| ( dev-libs/liblinux dev-libs/libbsd )" </section> +<section> +<title>Virtuals and subslots</title> + +<body> +<warning> +This section is only applicable if virtual providers include versions that +are ABI-compatible with one another (and use matching SONAMEs) and/or +the incompatible providers are being obsoleted. +</warning> + +<p> +Like regular packages, virtuals can define subslots that can be used +to trigger rebuilds of their reverse dependencies. For this to work, a new +version of the virtual is created for each subslot of the providers, +where each version contains dependencies on a specific subslot. +</p> + +<p> +For example, a virtual for different packages providing ABI-compatible +<c>libfoo.so.1</c> libraries could look like the following: +</p> + +<codesample lang="ebuild"> +EAPI=6 + +DESCRIPTION="Virtual for libfoo.so.1" +SLOT="0/1" + +RDEPEND=" + || ( + dev-libs/libfoo:0/1 + dev-libs/libfoo-alternate:0/1 + dev-libs/bigpack:0/libfoo-1+libbar-0 + dev-libs/bigpack:0/libfoo-1+libbar-1 + ) +" +</codesample> + +<p> +Virtuals can also be used when one of the providers is being obsoleted in favor +of another that breaks ABI compatibility while remaining API-compatible. In this +case, multiple versions of the virtual are created, each specifying a single +provider and a unique subslot. +</p> + +<p> +For example, if <c>dev-libs/libfoo</c> (<c>libfoo.so.0</c>) is being replaced +by <c>dev-libs/newfoo</c> (<c>libfoo.so.1</c>), <c>virtual/libfoo-0.ebuild</c> +would contain: +</p> + +<codesample lang="ebuild"> +EAPI=6 + +DESCRIPTION="Virtual for libfoo.so.0" +SLOT="0/0" +RDEPEND="dev-libs/libfoo:0/0" +</codesample> + +<p> +while <c>virtual/libfoo-1.ebuild</c> would contain: +</p> + +<codesample lang="ebuild"> +EAPI=6 + +DESCRIPTION="Virtual for libfoo.so.1" +SLOT="0/1" +RDEPEND="dev-libs/newfoo:0/1" +</codesample> + +<note> +In this case, the package manager will naturally want to upgrade +to <c>dev-libs/newfoo</c> whenever possible. Therefore, this solution +is not viable if clean choice between the two providers is desired. +</note> + +</body> +</section> + </chapter> </guide> |