X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=blobdiff_plain;f=README;h=14cc5420f4783f5f4568c73e58eab1c48f5759f9;hp=a44fb492b47301ea3bbbef8c102c645c5e4c9f8c;hb=9178f4c13177c6436d08182e1649d8476b4c3b8a;hpb=02276fc4ac88fc9cd85625c749ffe4305a8a69f8;ds=sidebyside

diff --git a/README b/README
index a44fb49..14cc542 100644
--- a/README
+++ b/README
@@ -88,13 +88,13 @@ empty string).
 
 &=		=>	sub_dir				or TOP
 
-&^lc		=>	$(top_srcdir)/sub/dir/lc
-&^/		=>	$(top_srcdir)/sub/dir/
-&^.		=>	$(top_srcdir)/sub/dir
+&^lc		=>	${top_srcdir}/sub/dir/lc
+&^/		=>	${top_srcdir}/sub/dir/
+&^.		=>	${top_srcdir}/sub/dir
 
-&~lc		=>	$(top_srcdir)/lc
-&~/		=>	$(top_srcdir)/
-&~.		=>	$(top_srcdir)
+&~lc		=>	${top_srcdir}/lc
+&~/		=>	${top_srcdir}/
+&~.		=>	${top_srcdir}
 
 In general:
     ^   pathname of this subdirectory in source tree
@@ -114,7 +114,7 @@ So pathname syntax is a subset of:
 &\$		=>	$		provided for $-doubling regimes
 &\NEWLINE				eats the newline and vanishes
 
-&$VARIABLE	=>	$(sub_dir_VARIABLE)	or $(TOP_VARIABLE)
+&$VARIABLE	=>	${sub_dir_VARIABLE}	or ${TOP_VARIABLE}
 	VARIABLE is ASCII starting with a letter and matching \w+
 
 & thing thing... &
@@ -205,6 +205,10 @@ Dollar doubling and macro assistance
 &$-		Stops dollar-doubling
 	Both are idempotent and local to the file or context.
 
+This is useful both for make macrology involving $(eval ...), and
+possibly for helping write complicated recipes involving shell
+variables, inline Perl code, etc.
+
 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.
@@ -233,8 +237,8 @@ $	=>	$$	including $'s produced by other
 			 &-expansions not mentioned here
 
 &\$	=>	$
-&$NN	=>	$(NN)	where N are digits
-&$(	=>	$(
+&$(	=>	${	(expands to { } so it is useable for shell too)
+&$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
@@ -334,7 +338,12 @@ suppressed with the &:warn directive.  The warning tags are:
 	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).
+	raw make: it expands to ${sub_dir_FOO}.
+
+    broken-var-ref
+        An attempt at variable expansion looking like $&...
+	You probably expected this to mean $(TOP_F)BAR but it
+	expands to $TOP_FBAR which make thinks means $(T)OP_FBAR.
 
     unknown-warning
 	&:warn was used to try to enable a warning that this version