Hi Ralf,
Hey, thanks for the response.
On 8/22/2009 1:59 AM, Ralf Wildenhues wrote:
Hello John,
* John Calcote wrote on Fri, Aug 21, 2009 at 02:44:03AM CEST:
I'm wondering about best practices for checking for programs like
the javac compiler. For instance, I currently have a line in my
project's configure.ac file that looks like this:
AC_CHECK_PROGS([JAVAC], ["gcj -C -ftarget=1.4 -fsource=1.4" "guavac
-target 1.4 -source 1.4" "jikes -target 1.4 -source 1.4" "javac
-target 1.4 -source 1.4"])
Why are you doing this? AC_CHECK_PROGS will cut off the arguments when
searching for the program anyway, it don't try to run the program.
The reason that *I* do this is so that the program variable (JAVAC) will
be set to the specified string (possibly prefixed with a path, if the
skip argument is used). For example, if gcj is found in the path, then
JAVAC should be set to "gcj -C". This is because, for gcj to act like
Sun's javac program, you need to pass the -C option (otherwise it will
compile Java sources to native code instead of Java byte code). But if
none of the programs is found until the search reaches javac, then JAVAC
should be set to just "javac".
This system was fine, when the *only* difference between programs was
the -C option on gcj. Then it made sense to just pass -C in the search
for gcj. But now that I need to specify target JVM and source version
restrictions, it seems silly to pass the same set of additional command
line options to all programs *except* gcj (which requires a slightly
different format for these options). If they were all the same, I'd just
add them to the JAVACFLAGS variable.
The semantics of AC_CHECK_PROGS are purely done so that one can pass in
variables to AC_CHECK_PROGS that are also used likewise elsewhere; but
for the tests done by this macro, they are not relevant.
Hmmm. I thought the point of being able to pass options to various
search programs in AC_CHECK_PROGS was to be able to conform run-time
characteristics of one of the programs to that of the others in the
list, if options were required in order to do so. Those options are then
pasted onto the command that's ultimately set in the variable. At least,
that's what the comments in the macro definition appear to be telling
the reader.
In fact, this works very well. When I use $(JAVAC) in my Makefile.am
files, I do get the correct options passed for the first located program
- "gcj -C -ftarget=1.4 -fsource=1.4" on my 64-bit linux system, and
"javac -target 1.4 -source 1.4" on systems with only the Sun java
compiler installed.
I was just asking if there's a better way to pass different options to
different commands found by AC_CHECK_PROGS, but in fact, I can't really
envision anything else that would work better. It just /feels/ like the
wrong place to do what I'm trying to do.
John
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