diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/bitbake-user-manual/bitbake-user-manual-metadata.xml | 117 |
1 files changed, 104 insertions, 13 deletions
diff --git a/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml b/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml index 47691af3b..82094b85c 100644 --- a/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml +++ b/doc/bitbake-user-manual/bitbake-user-manual-metadata.xml @@ -277,6 +277,15 @@ override syntax. </note> </para> + + <para> + It is also possible to append and prepend to shell + functions and BitBake-style Python functions. + See the + "<link linkend='shell-functions'>Shell Functions</link>" and + "<link linkend='bitbake-style-python-functions'>BitBake Style Python Functions</link> + sections for examples. + </para> </section> <section id='removing-override-style-syntax'> @@ -1090,6 +1099,56 @@ such as <filename>dash</filename>. You should not use Bash-specific script (bashisms). </para> + + <para> + Overrides and override-style operators like + <filename>_append</filename> and + <filename>_prepend</filename> can also be applied to + shell functions. + Most commonly, this application would be used in a + <filename>.bbappend</filename> file to modify functions in + the main recipe. + It can also be used to modify functions inherited from + classes. + </para> + + <para> + As an example, consider the following: + <literallayout class='monospaced'> + do_foo() { + bbplain first + fn + } + + fn_prepend() { + bbplain second + } + + fn() { + bbplain third + } + + do_foo_append() { + bbplain fourth + } + </literallayout> + The output from <filename>do_foo</filename> + results in the following: + <literallayout class='monospaced'> + recipename do_foo: first + recipename do_foo: second + recipename do_foo: third + recipename do_foo: fourth + </literallayout> + <note> + Overrides and override-style operators can + be applied to any shell function, not just + <link linkend='tasks'>tasks</link>. + </note> + You can use the <filename>bitbake -e</filename> <replaceable>recipename</replaceable> + command to view the final assembled function + after all overrides have been applied. + </para> </section> <section id='bitbake-style-python-functions'> @@ -1114,19 +1173,51 @@ Also in these types of functions, the datastore ("d") is a global variable and is always automatically available. - </para> - - <note> - Variable expressions (e.g. <filename>${X}</filename>) are no - longer expanded within Python functions. - This behavior is intentional in order to allow you to freely - set variable values to expandable expressions without having - them expanded prematurely. - If you do wish to expand a variable within a Python function, - use <filename>d.getVar("X", True)</filename>. - Or, for more complicated expressions, use - <filename>d.expand()</filename>. - </note> + <note> + Variable expressions (e.g. <filename>${X}</filename>) + are no longer expanded within Python functions. + This behavior is intentional in order to allow you + to freely set variable values to expandable expressions + without having them expanded prematurely. + If you do wish to expand a variable within a Python + function, use <filename>d.getVar("X", True)</filename>. + Or, for more complicated expressions, use + <filename>d.expand()</filename>. + </note> + </para> + + <para> + Similar to shell functions, you can also apply overrides + and override-style operators to BitBake-style Python + functions. + </para> + + <para> + As an example, consider the following: + <literallayout class='monospaced'> + python do_foo_prepend() { + bb.plain("first") + } + + python do_foo() { + bb.plain("second") + } + + python do_foo_append() { + bb.plain("third") + } + </literallayout> + The output from <filename>do_foo</filename> results + in the following: + <literallayout class='monospaced'> + recipename do_foo: first + recipename do_foo: second + recipename do_foo: third + </literallayout> + You can use the <filename>bitbake -e</filename> <replaceable>recipename</replaceable> + command to view the final assembled function + after all overrides have been applied. + </para> </section> <section id='python-functions'> |