X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=blobdiff_plain;f=README;h=360afbd351686e5f2d0ebfde1a486d5ac4967b40;hp=27dd8556a77c05ecd047b7aaa5aa23c3a7f2957e;hb=e41e8392b952e8412f2317de76eef3f698343a1d;hpb=411c2cad33613d6790cb819e8bd91a7f58a3998f

diff --git a/README b/README
index 27dd855..360afbd 100644
--- a/README
+++ b/README
@@ -183,7 +183,7 @@ In more detail, with all the various options laid out:
              for      build     source       build         source
                                                        
   This       lc       &file     &^file       $(PWD)/&file  $(abs_src)/&file
-  directory  any      &/file    &^/file      $(PWD)&/file  $(abs_src)/&/file
+  directory  any      &/file    &^/file      $(PWD)/&/file $(abs_src)/&/file
              several  & f g h   &^ f g h     $(addprefix...)
                                              
   Top        lc       file      &~file
@@ -218,30 +218,42 @@ empty string).
 	The assumption is that filenames are usually lowercase and
 	variables usually uppercase.  Otherwise, use another syntax:
 
+&/		=>	sub/dir/			or nothing
 &_		=>	sub_dir_			or TOP_
-&=_		=>	sub_dir				or TOP
+&.		=>	sub/dir				or .
+	(This implies that `&./' works roughly like `&/', although
+	it can produce a needless `./')
 
-&/		=>	sub/dir/			or nothing
-&=/		=>	sub/dir				or .
+&=		=>	sub_dir				or TOP
 
 &^lc		=>	$(top_srcdir)/sub/dir/lc
 &^/		=>	$(top_srcdir)/sub/dir/
+&^.		=>	$(top_srcdir)/sub/dir
 
 &~lc		=>	$(top_srcdir)/lc
 &~/		=>	$(top_srcdir)/
+&~.		=>	$(top_srcdir)
 
 In general:
-    =	return subdir without delimiter (not allowed with `^' `~')
     ^   pathname of this subdirectory in source tree
     ~   pathname of top level of source tree
-    /	terminates the escape (needed if next is not lwsp or space)
+    /	terminates the path escape } needed if next is
+    _   terminates the var escape  } not lwsp or space)
+    .   terminates path escape giving dir name (excluding /)
+    =	terminates var escape giving only prefix part (rarely needed)
   lwsp  starts multi-word processing (see below)
 
 So pathname syntax is a subset of:
-    '&' [ '^' | '~' ] [ lc | '/' ]
+    '&' [ '^' | '~' ] [ lc | '/' | '.' | '=' ]
 
 &&		=>	&&		for convenience in shell runes
-\&		=>	&		general escaping mechanism
+
+&\&		=>	&		general escaping mechanism
+&\$		=>	$
+&\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... &
@@ -255,35 +267,37 @@ So pathname syntax is a subset of:
 
 &:<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)
 
 &#	delete everything to end of line
 	(useful if the RHS contains unrecognised & constructions)
 
-&!STUFF
-	changes the escape sequence from & to literally STUFF
-	STUFF may be any series of of non-whitespace characters,
-	and is terminated by EOL or lwsp.  &!STUFF and the lwsp
-	are discarded.
+&:changequote NEWQUOTE
+	changes the escape sequence from & to literally NEWQUOTE
+	NEWQUOTE may be any series of of non-whitespace characters,
+	and is terminated by EOL or lwsp.  The whole line is
+	discarded.
 
-	After this, write STUFF instead of &, everywhere.
+	After this, write NEWQUOTE instead of &, everywhere.
 	The effect is global and lasts until the next setting.
 	It takes effect on &:include'd files too, so maybe set
 	it back before using &:include.
 
 	Notably
-		STUFFSTUFF	=>	STUFFSTUFF
-		\STUFF		=>	STUFF
-		STUFF!&		set escape back to &
+		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)
 
@@ -297,9 +311,9 @@ So pathname syntax is a subset of:
 	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.