--------------
The developer is expected to write a makefile fragment, in each
-relevant subdirectory, called `Subdir.sd.mk'.
+relevant subdirectory, called `Dir.sd.mk'.
These fragments may contain ordinary make language. Unqualified
filenames are relative to the build toplevel, and all commands all run
`the build directory corresponding to this .sd.mk file', etc.
There are a variety of convenient constructions.
-The result is that to a large extent, the Subdir.sd.mk has an easy way
+The result is that to a large extent, the Dir.sd.mk has an easy way
to namespace its "local" make variables, and an easy way to refer to
its "local" filenames (and filenames in general).
-The Subdir.sd.mk's are filtered, fed through autoconf in the usual way
+The Dir.sd.mk's are filtered, fed through autoconf in the usual way
(for @..@-substitutions) and included by one autogenerated toplevel
makefile.
which exists purely to capture ordinary make invocations and arrange
for something suitable to happen.
-Where there are dependencies between subdirectories, each Subdir.sd.mk
+Where there are dependencies between subdirectories, each Dir.sd.mk
can simply refer to files in other subdirectories directly.
Invocation, "recursive" per-directory targets
subdirectory `src' has a target `src/all'. The rules for these are
automatically generated from the settings of the per-directory
&TARGETS variables. &TARGETS is magic in this way. (In
-src/Subdir.sd.mk, &TARGETS of course refers to a make variable called
+src/Dir.sd.mk, &TARGETS of course refers to a make variable called
src_TARGETS.)
The `all' target in a parent directory is taken to imply the `all'
at a time. There is no sequencing between subdirectories, only been
individual targets (as specified according to their dependencies).
-You can define other per-directory recursive targets too: simply
-mention (usually, by setting) the variable &TARGETS_zonk, or whatever.
-This will create a src/zonk target (for appropriate value of src/).
-Unlike `all', these other targets only exist in areas of the project
-where at least something mentions them. So for example, if
-&TARGETS_zonk is mentioned in src but not lib, `make zonk' in
-lib will fail. If you want to make a target exist everywhere,
-mention its name in Perdir.sd.mk (see below).
+You can define other per-directory recursive targets too: set the
+variable &TARGETS_zonk, or whatever (being sure to write &TARGETS_zonk
+at the start of a line). This will create a src/zonk target (for
+appropriate value of src/). Unlike `all', these other targets only
+exist in areas of the project where at least something mentions them.
+So for example, if &TARGETS_zonk is set in src but not lib, `make
+zonk' in lib will fail. If you want to make a target exist
+everywhere, += it with nothing in Prefix.sd.mk or Suffix.sd.mk (see
+below).
-Perdir.sd.mk, inclusion
------------------------
+Prefix.sd.mk, Suffix.sd.mk, Final.sd.mk, inclusion
+--------------------------------------------------
-The file Perdir.sd.mk in the toplevel of the source is automatically
-processed after each individual directory's Subdir.sd.mk, and the
-&-substituted contents therefore appear once for each subdirectory.
+The files Prefix.sd.mk and Suffix.sd.mk in the toplevel of the source
+are automatically processed before and after each individual
+directory's Dir.sd.mk, and the &-substituted contents therefore
+appear once for each subdirectory.
This lets you do per-directory boilerplate. Some useful boilerplate
is already provided in subdirmk, for you to reference like this:
&:include subdirmk/cdeps.sd.mk
&:include subdirmk/clean.sd.mk
-For example you could put that in Perdir.sd.mk.
+For example you could put that in Suffix.sd.mk.
-The top-level Subdir.sd.mk is the first makefile included after the
+The top-level Dir.sd.mk is the first makefile included after the
autogenerated `main.mk' which merely has some basic settings and
includes. So if you want to get in early and set global variables,
-put them near the top of Subdir.sd.mk.
+put them near the top of Dir.sd.mk.
+
+The file Final.sd.mk in the toplevel directory is processed and
+included after all the other files.
subdirmk's filter script itself sets (only) these variables:
top_srcdir
------------------
If want to set global variables, such as CC, that should only be done
-once. You can put them in your top-level Subdir.sd.mk, or a separate
+once. You can put them in your top-level Dir.sd.mk, or a separate
file you `include' and declare using SUBDIRMK_MAKEFILES.
If you need different settings of variables like CC for different
subdirectories, you should probably do that with target-specific
variable settings. See the info node `(make) Target-specific'.
-Subdirectory templates `.sd.mk' vs plain autoconf templates `.mk.in'
+Directory templates `.sd.mk' vs plain autoconf templates `.mk.in'
--------------------------------------------------------------------
There are two kinds of template files.
Instantiated Usu. once per subdir Once only
- Need to be mentioned No, but Subdir.sd.mk All not in subdirmk/
+ Need to be mentioned No, but Dir.sd.mk All not in subdirmk/
in configure.ac? via SUBDIRMK_SUBDIRS via SUBDIRMK_MAKEFILES
How to include `&:include foo.sd.mk' `include foo.mk'
in all relevant .sd.mk in only one
- (but not needed for Subdir.sd.mk
- Subdir and Perdir)
+ (but not needed for Dir.sd.mk
+ Prefix, Suffix, Final)
If you `include subdirmk/regen.mk', dependency management and
automatic regeneration for all of this template substitution, and for
(i) In the build tree, or in the source tree ?
- (ii) In (or relative to) the subdirectory to which this Subdir.sd.mk
+ (ii) In (or relative to) the subdirectory to which this Dir.sd.mk
relates, or relative to the project's top level ?
(iii) Absolute or relative pathname ? Usually relative pathnames
&& => && for convenience in shell runes
&\& => & general escaping mechanism
-&\$ => $
+&\$ => $ provided for $-doubling regimes
+&\NEWLINE eats the newline and vanishes
+
+&$VARIABLE => $(sub_dir_VARIABLE) or $(TOP_VARIABLE)
+ VARIABLE is ASCII starting with a letter and matching \w+
& thing thing... &
&^ thing thing... &
&:<directive> <args>....
recognised at start of line only (possibly after lwsp)
- args are processed for &
-&:include filename filename should usually be foo.sd.mk
+&:include filename filename should usually be [&]foo.sd.mk
&:-include filename tolerate nonexistent file
filenames are relative to $(top_srcdir)
+ RHS is &-expanded
&!<lwsp> disables & until EOL (and then disappears)
Notably
NEWQUOTENEWQUOTE => NEWQUOTENEWQUOTE
NEWQUOTE\NEWQUOTE => NEWQUOTE
+ NEWQUOTE\$ => $
NEWQUOTE:changequote & set escape back to &
&TARGETS_things
- Handled specially. If mentioned, declares that this
+ Handled specially. If mentioned at the start of a line
+ (possibly following whitespace), declares that this
subdir ought to have a target `things'. The rule will be
&/things:: $(&TARGETS_things)
which recursively implies this directory's `things'.
Must be spelled exactly &TARGETS_things. &_TARGETS_things,
- for example, is not magic. But mentioning &TARGETS_things in
- a #-comment *does* work because the & filter does not care
- about comments.
+ for example, is not magic. To make the target exist
+ without providing any prerequisites for it, write a line
+ containing just `&TARGETS_things +='.
`all' is extra special: every directory has an `all'
target, which corresponds to &TARGETS.
+
+Dollar doubling and macro assistance
+------------------------------------
+
+&$+ Starts dollar-doubling
+&$- Stops dollar-doubling
+ Both are idempotent and local to the file or context.
+
+Sometimes we will show $'s being doubled inside another construct.
+This means the content of the construct is $-doubled: $-doubling is
+locally enabled, and restored afterwards.
+
+&:macro NAME => define NAME
+STUFF $ THINGS .. STUFF $$ THINGS
+&:endm .. endef
+ NAME is processed for &
+
+&${..$..} => ${eval ${call ..$$..}}
+ (matches { } pairs to find the end)
+ content is $-doubled (unless it contains $- to turn that off)
+
+ Together &:macro and &${...} provide a more reasonable macro
+ facility than raw make. They solve the problem that make
+ expansions cannot directly generate multiple rules, variable,
+ etc.; instead, `$(eval )' must be used, but that re-expands
+ the argument, meaning that all the literal text must be
+ $-doubled. This applies to the macro text and to the
+ arguments. Also `$(eval $(call ...))' is an unfortunate syntax.
+ Hence &:macro and &${...}.
+
+While dollar-doubling:
+- - - - - - - - - - -
+
+$ => $$ including $'s produced by other
+ &-expansions not mentioned here
+
+&\$ => $
+&$NN => $(NN) where N are digits
+&$( => $(
+
+
Subdirectory and variable naming
--------------------------------
m4_include([subdirmk/subdirmk.ac])
SUBDIRMK_SUBDIRS([...list of subdirectories in relative syntax...])
-Write a Subdir.sd.mk in each directory. The toplevel one should
+Write a Dir.sd.mk in each directory. The toplevel one should
probably contain:
include subdirmk/usual.mk
include subdirmk/regen.mk
-Write a Perdir.sd.mk in the toplevel, if you want. It should probably
+Write a Suffix.sd.mk in the toplevel, if you want. It should probably
have:
&:include subdirmk/cdeps.sd.mk
-----
You can convert your project incrementally. Start with the top-level
-Makefile.in and rename it to Subdir.sd.mk, and add the appropriate
+Makefile.in and rename it to Dir.sd.mk, and add the appropriate
stuff to configure.ac, and fix everything up. Leave the existing
$(MAKE) -C for your existing subdirectories alone. Then you can
convert individual subdirectories, or classes of subdirectories, at