X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=blobdiff_plain;f=README;h=67ce6cc17c8fd3755ecddf39a675a073850f11ff;hp=cfd7ad03d1853cc3b8e68b6847ee1df079d401ca;hb=503a7e5169b4a18e2ad2569daeb9e13a99f21070;hpb=c0b216c79763f720df20e002fc14c9348a0e05c2

diff --git a/README b/README
index cfd7ad0..67ce6cc 100644
--- a/README
+++ b/README
@@ -174,22 +174,22 @@ Path construction &-expansions are built from the following:
                       Relative paths in...
                       build     source
                                                        
-  This directory      &         &,
-  Top level           .         &;
+  This directory      &         &^
+  Top level           .         &~
 
 In more detail, with all the various options laid out:
 
       Recommended     Relative paths in...   Absolute paths in...
              for      build     source       build         source
                                                        
-  This       lc       &file     &,file       $(PWD)/&file  $(abs_src)/&file
-  directory  any      &/file    &,/file      $(PWD)&/file  $(abs_src)/&/file
-             several  & f g h   &, f g h     $(addprefix...)
+  This       lc       &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
-  level      any      file      &;/file      $(PWD)/file   $(abs_src)/file
+  Top        lc       file      &~file
+  level      any      file      &~/file      $(PWD)/file   $(abs_src)/file
              .mk.in   file      $(src)/file  $(PWD)/file   $(abs_src)/file
-             several  f g h     &; f g h     $(addprefix...)
+             several  f g h     &~ f g h     $(addprefix...)
 
 (This assumes you have appropriate make variables src, PWD and
 abs_src.)
@@ -218,34 +218,40 @@ 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/
+&^lc		=>	$(top_srcdir)/sub/dir/lc
+&^/		=>	$(top_srcdir)/sub/dir/
+&^.		=>	$(top_srcdir)/sub/dir
 
-&;lc		=>	$(top_srcdir)/lc
-&;/		=>	$(top_srcdir)/
+&~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)
+    ^   pathname of this subdirectory in source tree
+    ~   pathname of top level of source tree
+    /	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
 
 & thing thing... &
-&, thing thing... &
-&; thing thing... &
+&^ thing thing... &
+&~ thing thing... &
 	Convenience syntax for prefixing multiple filenames.
 	Introduced by & followed by lwsp where lc could go.
 	Each lwsp-separated non-ws word is prefixed by &/ etc.
@@ -266,11 +272,11 @@ So pathname syntax is a subset of:
 &#	delete everything to end of line
 	(useful if the RHS contains unrecognised & constructions)
 
-&!STUFF
+&:changequote 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.
+	and is terminated by EOL or lwsp.  The whole line is
+	discarded.
 
 	After this, write STUFF instead of &, everywhere.
 	The effect is global and lasts until the next setting.
@@ -278,9 +284,9 @@ So pathname syntax is a subset of:
 	it back before using &:include.
 
 	Notably
-		STUFFSTUFF	=>	STUFFSTUFF
-		\STUFF		=>	STUFF
-		STUFF!&		set escape back to &
+		STUFFSTUFF		=> STUFFSTUFF
+		\STUFF			=> STUFF
+		STUFF:changequote &	=> set escape back to &
 
 &TARGETS_things
 	Handled specially.  If mentioned, declares that this
@@ -371,6 +377,13 @@ makefiles, you may find that just `make' is broken now and cannot get
 far enough to regenerate a working set of makefiles.  If this happens
 just rerun ./config.status by hand.
 
+If you go back and forth between different versions of your code you
+can sometimes find that `make' complains that one of your Subdir.sd.mk
+files is missing: typically, if iot was used and therefore a
+dependency in some other version of your code.  If you run `make
+clean' (or `make realclean') these dependencies are suppressed, which
+will clear up the problem.
+
 
 Legal information
 -----------------