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| author |   Robert P. J. Day <rpjday@crashcourse.ca> | 2014-07-10 10:12:09 +0300 |
|---|---|---|
| committer |   Richard Purdie <richard.purdie@linuxfoundation.org> | 2014-07-21 11:00:57 +0100 |
| commit | 49627bbad387791053e50dde02b51a0f16fdc40e (patch) | |
| tree | 6b05f0106c8c2b17e1c972f4a9408a8b955e873b | |
| parent | e83032ce0a3f847e6a8fd5f5b64ee6aa7ec6b404 (diff) | |
| download | openembedded-core-contrib-49627bbad387791053e50dde02b51a0f16fdc40e.tar.gz | |
bitbake: bitbake-user-manual-metadata.xml: Adding some flag examples.
As long as i've understood everything correctly, this is just
throwing in some physical examples of a couple concepts.
(Bitbake rev: a18cc69c2fef6484a6acd78ea008d1da71198e68)
Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
| -rw-r--r-- | bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml | 25 |
1 files changed, 24 insertions, 1 deletions
diff --git a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml index b8a77e1fa0..5e1a381fac 100644 --- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml +++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml @@ -293,6 +293,17 @@ The flags are immediately set to "abc" and "123", respectively. The <filename>a</filename> flag becomes "abc456". </para> + + <para> + No need exists to pre-define variable flags. + You can simply start using them. + One extremely common application + is to attach some brief documentation to a BitBake variable as + follows: + <literallayout class='monospaced'> + CACHE[doc] = "The directory holding the cache of the metadata." + </literallayout> + </para> </section> <section id='inline-python-variable-expansion'> @@ -306,7 +317,19 @@ DATE = "${@time.strftime('%Y%m%d',time.gmtime())}" </literallayout> This example results in the <filename>DATE</filename> - variable becoming the current date. + variable being set to the current date. + </para> + + <para> + Probably the most common use of this feature is to extract + the value of variables from BitBake's internal data dictionary, + <filename>d</filename>. + The following lines select the values of a package name + and its version number, respectively: + <literallayout class='monospaced'> + PN = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[0] or 'defaultpkgname'}" + PV = "${@bb.parse.BBHandler.vars_from_file(d.getVar('FILE'),d)[1] or '1.0'}" + </literallayout> </para> </section> |