From 0a6ac67828982aca4e3c8ac73669420a30c70f34 Mon Sep 17 00:00:00 2001 From: Ian Jackson Date: Thu, 14 Nov 2019 14:54:48 +0000 Subject: [PATCH] docs: Abolish all absolute pathname syntaxes These are rare and make things much more confusing. Signed-off-by: Ian Jackson --- README | 62 ++++++++++++++++++++++++++-------------------------------- 1 file changed, 28 insertions(+), 34 deletions(-) diff --git a/README b/README index ef839d5..c9e4c0f 100644 --- a/README +++ b/README @@ -152,30 +152,34 @@ locations: (ii) In (or relative to) the subdirectory to which this Subdir.sd.mk relates, or relative to the project's top level ? - (iii) Absolute or relative pathname ? - (Usually relative pathnames suffice.) + (iii) Absolute or relative pathname ? Usually relative pathnames + suffice. Where an absolute pathname is needed, it can be built + out of &/ and an appropriate make variable such as $(PWD). Path construction &-expansions are built from the following: - Relative paths in... Absolute paths in... - build source build source + Relative paths in... + build source - This directory & &, &@ &@, - Top level . &; &@. &@; + This directory & &, + Top level . &; -In more detail, with the various options for what comes next: +In more detail, with all the various options laid out: Recommended Relative paths in... Absolute paths in... - for build source build source + for build source build source - This lc &file &,file &@file &@,file - directory any &/file &,/file &@/file &@,/file - several & f g h &, f g h &@ f g h &@, f g h + 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 &@.file &@;file - level any file &;/file &@./file &@;/file - several f g h &; f g h &@. f g h &@; f g h - .mk.in file $(src)/file $(abs)/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...) + +(This assumes you have appropriate make variables src, PWD and +abs_src.) Substitution syntax ------------------- @@ -207,38 +211,28 @@ empty string). &/ => sub/dir/ or nothing &=/ => sub/dir or . -&,lc => $(top_srcdir)/sub/dir/lc &,/ => $(top_srcdir)/sub/dir/ -&;lc => $(top_srcdir)/lc &;/ => $(top_srcdir)/ +&,lc => $(top_srcdir)/sub/dir/lc +&,/ => $(top_srcdir)/sub/dir/ -&@lc => $(PWD)/sub/dir/lc &@/ => $(PWD)/sub/dir/ -&@.lc => $(PWD)/lc &@./ => $(PWD)/ -&@,lc => $(abs_top_srcdir)/sub/dir/lc &@,/ => $(abs_top_srcdir)/sub/dir/ -&@;lc => $(abs_top_srcdir)/lc &@;/ => $(abs_top_srcdir)/ +&;lc => $(top_srcdir)/lc +&;/ => $(top_srcdir)/ In general: - = return subdir without delimiter (not allowed with `,' `;' `@') + = return subdir without delimiter (not allowed with `,' `;') , pathname of this subdirectory in source tree ; pathname of top level of source tree - . pathname of this directory in build tree, `@' must be specified - @ absolute pathnames / 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 | '/' ] - - To avoid incomprehensible .sd.mk files, some combinations are not - allowed. For example `&=./' would mean `.' and `&./' would be the - empty string. Variations with `=' and one of `@' `,' `;' are - uncommon and must be written using make variables instead. + '&' [ ',' | ';' ] [ lc | '/' ] && => && for convenience in shell runes \& => & general escaping mechanism -& thing thing... & &@ thing thing... & - &. thing thing... & -&, thing thing... & &@, thing thing... & -&; 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. -- 2.30.2