Re: Use of really long lines in Makefile.in

[Alexandre Duret-Lutz]

>>> "J" == J T Conklin <address@hidden> writes:

 J> Albert Chin <address@hidden> writes:
 >> So, should automake change lines like:
 >> foo_SOURCES = [long list of sources]
 >> to the following in Makefile.in:
 >> foo_SOURCES = $(foo_SOURCES_1) $(foo_SOURCES_2) ...
 >> foo_SOURCES_1 = [list of sources < 2048 chars]
 >> foo_SOURCES_2 = [list of sources < 2048 chars]
 >> ...

Regardless of what we decide for Automake, isn't the input
foo_SOURCES already >= 2048 chars?  Shouldn't it be fixed too?

AFAIC I find it so much easier to edit and diff Makefile.am in
which sources files are listed vertically

foo_SOURCES = \
  a.c \
  a.h \
  b.c \
  ...

that I hardly understand how one works with >2048-char lines.

 J> automake's 1.9 NEWS entry includes:
 J> - Variables aumented with `+=' are now automatically flattened (i.e.,
 J> trailing backslashes removed) and then wrapped around 80 colummns
 J> (adding trailing backslashes).  In previous versions, a long series
 J> of
 J> VAR += value1
 J> VAR += value2
 J> VAR += value3
 J> ...
 J> would result in a single-line definition of VAR that could possibly
 J> exceed the maximum line length of some make implementations.

Here "flattened" means that

| FOO = \
|   asdkjaslkjdas \
|   asldkjasldkj \
|   a;sdlkas;lsdka; \
|   a;sdjadksa \
|   asdsa
| FOO += bar asldkasj laskjd alkj daslk j

becomes

| FOO = asdkjaslkjdas asldkjasldkj a;sdlkas;lsdka; a;sdjadksa \
|         asdsa bar asldkasj laskjd alkj daslk j

 J> Non-augmented variables are still output as they are defined in
 J> the Makefile.am.

One reason I did this only for `+=' variables is that I was
really leery of changing the layout of the variables defined by
the user.  Normally Automake tries to output definitions as
it reads them.  Variables used with += are usually list of
files, and they were already output differently by Automake, so
such flattening didn't seem too harmful.  For other variables I
was less sure (for instance I can imagine people grepping
Makefiles for some pattern they used in Makefile.ams).

 J> flattening non-augmented variable assignments seems like a better
 J> solution to the problem of too long lines.

Maybe Automake could do that if the variable appear to be longer
than some "human tolerance" threshold.  Assume a generated file
list and flatten any variable definition with more that 500
characters in a line.  This way ordinary variables are still
output exactly as defined.

(I feeling a bit paranoid here; the above scheme is likely to be
overkill.)
-- 
Alexandre Duret-Lutz