&${..$..} => ${eval ${call ..$$..}}
(matches { } pairs to find the end)
- content is $-doubled (unless it contains $- to turn that off)
+ 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 $(call ...))' is an unfortunate syntax.
- Hence &:macro and &${...}.
+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:
- - - - - - - - - - -
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.
+the result included after all the other files. Its subdirmk
+filtering context inherits warning suppressions from the toplevel's
+Dir.sd.mk etc., but not anything else.
subdirmk's filter script itself sets (only) these variables:
top_srcdir
You are likely to want to define $(PWD), and shorter names for
top_srdir and abs_top_srcdir (we suggest $(src) and $(abs_src)).
+Warnings
+--------
+
+subdirmk's `generate' program, which does the acual &-substitution,
+can produce some warnings about your .sd.mk files. These can be
+suppressed with the &:warn directive. The warning tags are:
+
+ local+global
+ The same VARNAME was used both with and without an & prefix.
+ This can be confusing. Also, if you avoid this then you will
+ get a warning iff you accidentally leave off a needed &.
+ The generation of this warning depends on scanning your
+ makefile for things that look like variable references, which
+ subdirmk does not do completely perfectly. Exciting make
+ syntax may evade this warning, or require suppressions.
+ (You can suppress this warning for a particular VARNAME with
+ the &:local+global directive.)
+
+ single-char-var
+ A variable expansion like $FBAR. make's expansion rules
+ interpret this as $(F)BAR. It's normally better to write
+ it this way, at least if the variable expansion is followed
+ by more letters. Note that &$FOO works differently to
+ raw make: it expands to $(sub_dir_FOO).
+
+ unknown-warning
+ &:warn was used to try to enable a warning that this version
+ of subdirmk does not understand. (Note that an attempt to
+ *dis*able an unknown warning is only reported if some other
+ warning was issued which might have been disabled.)
+
+
+Guides, hints, and further explanations
+=======================================
+
Global definitions
------------------
subdirectories, you should probably do that with target-specific
variable settings. See the info node `(make) Target-specific'.
+
Directory templates `.sd.mk' vs plain autoconf templates `.mk.in'
--------------------------------------------------------------------
(This assumes you have appropriate make variables src, PWD and
abs_src.)
-Warnings
---------
-
-subdirmk's `generate' program, which does the acual &-substitution,
-can produce some warnings about your .sd.mk files. These can be
-suppressed with the &:warn directive. The warning tags are:
-
- local+global
- The same VARNAME was used both with and without an & prefix.
- This can be confusing. Also, if you avoid this then you will
- get a warning iff you accidentally leave off a needed &.
- (You can suppress this warning for a particular VARNAME with
- the &:local+global directive.)
-
- single-char-var
- A variable expansion like $FBAR. make's expansion rules
- interpret this as $(F)BAR. It's normally better to write
- it this way, at least if the variable expansion is followed
- by more letters. Note that &$FOO works differently to
- raw make: it expands to $(sub_dir_FOO).
-
- unknown-warning
- &:warn was used to try to enable a warning that this version
- of subdirmk does not understand. (Note that an attempt to
- *dis*able an unknown warning is only reported if some other
- warning was issued which might have been disabled.)
Subdirectory and variable naming
--------------------------------
Legal information
------------------
+=================
subdirmk is
Copyright 2019 Mark Wooding
~ianmdlvl / secnet.git / blobdiff