Re: i need some smart rule

[Paul D. Smith]

%% Maciej Walezak <address@hidden> writes:

  mw> Hello,

  mw> I need several rules that would link binary files and each of them
  mw> with different commands, i.e. one for binaries from objects from C
  mw> sources, one for binaries from objects from C++ sources and one
  mw> for Fortran.

In general, if you can't distinguish between the lists of object files
to tell which executables should be built using what commands, then
there's no way make can do so either.

  mw> My current solution is
  mw> $(bin)/$(cbin):
  mw>   command1
  mw> $(bin)/$(ccbin):
  mw>   command2
  mw> $(bin)/$(fbin):
  mw>   command3

  mw> I do not like this solution as it requires that appropriate
  mw> variable is defined and it prevents me from linking more that one
  mw> binary in single makefile (cbin is set to a concrete file).

  mw> Is there a way to write these rules in more flexible way?

Well, you can do something like this:

  $(cbins:%=$(bin)/%):
        ...build from .c files...

  $(ccbins:%=$(bin)/%):
        ...build from .cc files...

  $(fbins:%=$(bin)/%):
        ...build from .f files...


Now you can set "cbins" to a list of executables, like this:

  cbins = foo bar baz

  foo: foo.o biz.o

  bar: bar.o bong.o

  baz: baz.o bloz.o


Note that a rule that has an empty target is ignored, so you won't get
errors if one or more of the variables doesn't have a value.  But, if
you don't want to rely on this you can always do something like:

  ifdef cbins
    $(cbins:%=$(bin)/%):
        ...build from .c files...
  endif

  ifdef ccbins
    $(ccbins:%=$(bin)/%):
        ...build from .cc files...
  endif

  ifdef fbins
    $(fbins:%=$(bin)/%):
        ...build from .f files...
  endif

or whatever.

-- 
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 Paul D. Smith <address@hidden>          Find some GNU make tips at:
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