X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=blobdiff_plain;f=README;h=006b57f62eaeacb6cb0927dcfe67b3968121e15b;hp=c9e4c0f9234f2fe42bac8187dd98c88784bb417a;hb=c6e0abe539310d9c3a612dd92f59d106aa8674c7;hpb=0a6ac67828982aca4e3c8ac73669420a30c70f34

diff --git a/README b/README
index c9e4c0f..006b57f 100644
--- a/README
+++ b/README
@@ -105,6 +105,19 @@ is already provided in subdirmk, for you to reference like this:
   &:include subdirmk/clean.sd.mk
 For example you could put that in Perdir.sd.mk.
 
+The top-level Subdir.sd.mk is the first makefile included after the
+autogenerated `main.mk' which merely has some basic settings and
+includes.  So if you want to get in early and set global variables,
+put them near the top of Subdir.sd.mk.
+
+subdirmk's filter script itself sets (only) these variables:
+  top_srcdir
+  abs_top_srcdir
+  SUBDIRMK_MAKEFILES
+  MAKEFILE_TEMPLATES
+You are likely to want to define $(PWD), and shorter names for
+top_srdir and abs_top_srcdir (we suggest $(src) and $(abs_src)).
+
 Global definitions
 ------------------
 
@@ -161,22 +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.)
@@ -211,28 +224,28 @@ empty string).
 &/		=>	sub/dir/			or nothing
 &=/		=>	sub/dir				or .
 
-&,lc		=>	$(top_srcdir)/sub/dir/lc
-&,/		=>	$(top_srcdir)/sub/dir/
+&^lc		=>	$(top_srcdir)/sub/dir/lc
+&^/		=>	$(top_srcdir)/sub/dir/
 
-&;lc		=>	$(top_srcdir)/lc
-&;/		=>	$(top_srcdir)/
+&~lc		=>	$(top_srcdir)/lc
+&~/		=>	$(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
+    =	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)
   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.
@@ -253,11 +266,11 @@ 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.
@@ -265,9 +278,9 @@ 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
@@ -358,6 +371,13 @@ 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
 -----------------