&:<directive> <args>....
recognised at start of line only (possibly after lwsp)
+&: => &:
+ for make multiple targets syntax
+ recognised anywhere *except* start of line
+
&:include filename filename should usually be [&]foo.sd.mk
&:-include filename tolerate nonexistent file
RHS is &-expanded but filenames are relative to the top
`all' is extra special: every directory has an `all'
target, which corresponds to &TARGETS.
+Directives
+- - - - -
+
&:warn [!]WARNTAG ...
Suppress (with !) or re-enable (without !) warnings tagged
WARNTAG (see section `Warnings', below). The suppression list
&:endm .. endef
NAME is processed for &
-&${..$..} => ${eval ${call ..$$..}}
+&{..$..} => ${eval ${call ..$$..}}
(matches { } pairs to find the end)
content is $-doubled (unless it contains &$- to turn that off)
+ contrast &(...), see "Convenience syntax for call", below.
-Together &:macro and &${...} provide a more reasonable macro facility
+Together &:macro and &{...} provide a more reasonable macro facility
than raw make. They solve the problem that make expansions cannot
-directly generate multiple rules, variable, etc.; instead, `$(eval )'
+directly generate multiple rules, variables, 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 $(call ...))' is an unfortunate syntax.
-Hence &:macro and &${...}.
+Hence &:macro and &{...}.
While dollar-doubling:
- - - - - - - - - - -
&-expansions not mentioned here
&\$ => $
-&$( => ${ (expands to { } so it is useable for shell too)
+&$( => $(
&$NN => ${NN} where N are digits
A few contexts do not support $-doubling, such as directive arguments
or places where this might imply $-quadrupling. (There is no way to
get $-quadrupling.)
+Convenience syntax for call
+- - - - - - - - - - - - - -
+
+&(thing => $(call thing
+&( thing => $(call thing
+ and specially:
+&(&lc => $(call sub_dir_lc or $(call TOP_lc
+&( &lc => $(call sub_dir_lc or $(call TOP_lc
+ even though lc would normally be thought a filename
+
+Unlike &{...}, this does not involve any dollar-doubling.
+
+Use this when the expansion is going to be a piece of text to be used
+as part of a rule, filename, etc. When the expansion is top-level
+make text (eg, rules), use &:macro and &{...}.
+
Invocation, "recursive" per-directory targets
---------------------------------------------
=================
subdirmk is
+ Copyright 2019-2020 Ian Jackson
Copyright 2019 Mark Wooding
- Copyright 2019 Ian Jackson
subdirmk and its example is free software; you can redistribute it
and/or modify it under the terms of the GNU Library General Public