doctests: Extract and use

[subdirmk.git] / README

diff --git a/README b/README
index 518dd087d853308b13e07aab805349714288d26e..4da40911ce83909e880874de657b6d4db797992b 100644 (file)
--- 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 +218,38 @@ 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
+&\$            =>      $
 
 & thing thing... &
 &^ thing thing... &
@@ -266,21 +274,21 @@ So pathname syntax is a subset of:
 &#     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:changequote &  set escape back to &
 
 &TARGETS_things
        Handled specially.  If mentioned, declares that this
@@ -371,6 +379,13 @@ 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
 -----------------