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authorScott Rifenbark <scott.m.rifenbark@intel.com>2014-04-14 09:34:39 -0700
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-04-21 23:03:19 +0100
commitea4e822b8d6d67a7264e9f7b2930606e23d36a73 (patch)
tree138f3f81a40a170c008782c72b1d9d4c73d45075 /bitbake/doc/bitbake-user-manual
parent9889a91a5b84175b91fec05b7a40234f72ac09b2 (diff)
downloadpoky-ea4e822b8d6d67a7264e9f7b2930606e23d36a73.tar.gz
bitbake: bitbake-user-manual-metadata.xml: New section on anonymous Python functions
Per Paul Eggleton's suggestion, I added a new section on anonymous Python functions into the "Functions" section. I also updated the intro text to account for the added type of functions. (Bitbake rev: 983d03c1a082e2b83187f0788e61a7941670b242) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Diffstat (limited to 'bitbake/doc/bitbake-user-manual')
-rw-r--r--bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml42
1 files changed, 41 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 365c4b8f97..5304e40ce7 100644
--- a/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
+++ b/bitbake/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml
@@ -683,7 +683,7 @@
683 <para> 683 <para>
684 As with most languages, functions are the building blocks that 684 As with most languages, functions are the building blocks that
685 are used to build up operations into tasks. 685 are used to build up operations into tasks.
686 BitBake supports three types of functions: 686 BitBake supports these types of functions:
687 <itemizedlist> 687 <itemizedlist>
688 <listitem><para><emphasis>Shell Functions:</emphasis> 688 <listitem><para><emphasis>Shell Functions:</emphasis>
689 Functions written in shell script and executed either 689 Functions written in shell script and executed either
@@ -697,6 +697,10 @@
697 <listitem><para><emphasis>Python Functions:</emphasis> 697 <listitem><para><emphasis>Python Functions:</emphasis>
698 Functions written in Python and executed by Python. 698 Functions written in Python and executed by Python.
699 </para></listitem> 699 </para></listitem>
700 <listitem><para><emphasis>Anonymous Python Functions:</emphasis>
701 Python functions executed automatically during
702 parsing.
703 </para></listitem>
700 </itemizedlist> 704 </itemizedlist>
701 Regardless of the type of function, you can only 705 Regardless of the type of function, you can only
702 define them in class (<filename>.bbclass</filename>) 706 define them in class (<filename>.bbclass</filename>)
@@ -793,6 +797,39 @@
793 </para> 797 </para>
794 </section> 798 </section>
795 799
800 <section id='anonymous-python-functions'>
801 <title>Anonymous Python Functions</title>
802
803 <para>
804 Sometimes it is useful to run some code during
805 parsing to set variables or to perform other operations
806 programmatically.
807 To do this, you can define an anonymous Python function.
808 Here is an example that conditionally sets a
809 variable based on the value of another variable:
810 <literallayout class='monospaced'>
811 python __anonymous () {
812 if d.getVar('SOMEVAR', True) == 'value':
813 d.setVar('ANOTHERVAR', 'value2')
814 }
815 </literallayout>
816 The "__anonymous" function name is optional, so the
817 following example is functionally equivalent to the above:
818 <literallayout class='monospaced'>
819 python () {
820 if d.getVar('SOMEVAR', True) == 'value':
821 d.setVar('ANOTHERVAR', 'value2')
822 }
823 </literallayout>
824 Because unlike other Python functions anonymous
825 Python functions are executed during parsing, the
826 "d" variable within an anonymous Python function represents
827 the datastore for the entire recipe.
828 Consequently, you can set variable values here and
829 those values can be picked up by other functions.
830 </para>
831 </section>
832
796 <section id='flexible-inheritance-for-class-functions'> 833 <section id='flexible-inheritance-for-class-functions'>
797 <title>Flexible Inheritance for Class Functions</title> 834 <title>Flexible Inheritance for Class Functions</title>
798 835
@@ -817,6 +854,9 @@
817 respectively, or it can redefine the function completely. 854 respectively, or it can redefine the function completely.
818 However, if it redefines the function, there is 855 However, if it redefines the function, there is
819 no means for it to call the class version of the function. 856 no means for it to call the class version of the function.
857 <filename>EXPORT_FUNCTIONS</filename> provides a mechanism
858 that enables the recipe's version of the function to call
859 the original version of the function.
820 </para> 860 </para>
821 861
822 <para> 862 <para>