kumquat-buildroot/docs/manual/writing-rules.txt
Julien Viard de Galbert 5284dcf7de Document the 72 char limit on package description.
While describing a package I though that the tab and 2 spaces was
already doing the margin for wrapping the help test (ie 70 char when
wrapping to 80) but apparently the full text need to fit 72 columns.

So this patch propose to document that fact in the two places where
the Config.in format is described.

Signed-off-by: Julien Viard de Galbert <julien@vdg.name>
Acked-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
2015-07-13 12:16:45 +02:00

144 lines
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// -*- mode:doc; -*-
// vim: set syntax=asciidoc:
== Coding style
Overall, these coding style rules are here to help you to add new files in
Buildroot or refactor existing ones.
If you slightly modify some existing file, the important thing is
to keep the consistency of the whole file, so you can:
* either follow the potentially deprecated coding style used in this
file,
* or entirely rework it in order to make it comply with these rules.
[[writing-rules-config-in]]
=== +Config.in+ file
+Config.in+ files contain entries for almost anything configurable in
Buildroot.
An entry has the following pattern:
---------------------
config BR2_PACKAGE_LIBFOO
bool "libfoo"
depends on BR2_PACKAGE_LIBBAZ
select BR2_PACKAGE_LIBBAR
help
This is a comment that explains what libfoo is.
http://foosoftware.org/libfoo/
---------------------
* The +bool+, +depends on+, +select+ and +help+ lines are indented
with one tab.
* The help text itself should be indented with one tab and two
spaces.
* The help text should be wrapped to fit 72 columns.
The +Config.in+ files are the input for the configuration tool
used in Buildroot, which is the regular _Kconfig_. For further
details about the _Kconfig_ language, refer to
http://kernel.org/doc/Documentation/kbuild/kconfig-language.txt[].
[[writing-rules-mk]]
=== The +.mk+ file
* Header: The file starts with a header. It contains the module name,
preferably in lowercase, enclosed between separators made of 80 hashes. A
blank line is mandatory after the header:
+
---------------------
################################################################################
#
# libfoo
#
################################################################################
---------------------
+
* Assignment: use +=+ preceded and followed by one space:
+
---------------------
LIBFOO_VERSION = 1.0
LIBFOO_CONF_OPTS += --without-python-support
---------------------
+
Do not align the +=+ signs.
* Indentation: use tab only:
+
---------------------
define LIBFOO_REMOVE_DOC
$(RM) -fr $(TARGET_DIR)/usr/share/libfoo/doc \
$(TARGET_DIR)/usr/share/man/man3/libfoo*
endef
---------------------
+
Note that commands inside a +define+ block should always start with a tab,
so _make_ recognizes them as commands.
* Optional dependency:
** Prefer multi-line syntax.
+
YES:
+
---------------------
ifeq ($(BR2_PACKAGE_PYTHON),y)
LIBFOO_CONF_OPTS += --with-python-support
LIBFOO_DEPENDENCIES += python
else
LIBFOO_CONF_OPTS += --without-python-support
endif
---------------------
+
NO:
+
---------------------
LIBFOO_CONF_OPTS += --with$(if $(BR2_PACKAGE_PYTHON),,out)-python-support
LIBFOO_DEPENDENCIES += $(if $(BR2_PACKAGE_PYTHON),python,)
---------------------
** Keep configure options and dependencies close together.
* Optional hooks: keep hook definition and assignment together in one
if block.
+
YES:
+
---------------------
ifneq ($(BR2_LIBFOO_INSTALL_DATA),y)
define LIBFOO_REMOVE_DATA
$(RM) -fr $(TARGET_DIR)/usr/share/libfoo/data
endef
LIBFOO_POST_INSTALL_TARGET_HOOKS += LIBFOO_REMOVE_DATA
endif
---------------------
+
NO:
+
---------------------
define LIBFOO_REMOVE_DATA
$(RM) -fr $(TARGET_DIR)/usr/share/libfoo/data
endef
ifneq ($(BR2_LIBFOO_INSTALL_DATA),y)
LIBFOO_POST_INSTALL_TARGET_HOOKS += LIBFOO_REMOVE_DATA
endif
---------------------
=== The documentation
The documentation uses the
http://www.methods.co.nz/asciidoc/[asciidoc] format.
For further details about the http://www.methods.co.nz/asciidoc/[asciidoc]
syntax, refer to http://www.methods.co.nz/asciidoc/userguide.html[].