C, Eclipse and multiple object files

[Steve]

Hi guys,

I have an Eclipse C project that currently spits out an executable binary.

I want to have part of the project compiled into a shared object file and then have the rest compiled into an executable.

Seems I can only have one or the other; what am I missing?

Cheers,
Steve.

[Fraz]

Seems I can only have one or the other; what am I missing?

I presume you are doing this with a managed make file right?

I'm not sure of the solution exactly, but have you tried splitting the code into two projects, one project compiled to a .so/.dll the other compiled as an executable.

Alternatively, you could write your own make file.

[Steve]

My fallback is to split into two projects, but I'd rather not - guess it doesn't really make much difference if I do, though.

And yes, I'm letting eclipse manage the makefile, perhaps I should get a bit more involved.

edit: Looks like I might be able to do it with multiple make targets. I'll have a go at that after lunch.

[aidanjt]

You'll need to manually edit your make files. It's fairly straight forward unless your project begins to get seriously unwieldy.

[Fraz]

And yes, I'm letting eclipse manage the makefile, perhaps I should get a bit more involved.

Best avoided if you can. I hate Makefiles with a passion.

They're fine once you've got them working, but the problem for me is that you only need to write them once in a blue moon, and when it comes round to fixing one or writing a new one, you've completely forgot how they work again, and it just looks like someone has vomited a load of random symbols into a text file...

[Fraz]

For instance, an excerpt from one of my projects:

# Generate the wrapper code with swig
$(SwigDir)/common/$(PyModuleName)_wrap.cc : $(SwigHeaderDir)/$(PyModuleName).i 
	$(SWIG) -shadow -c++ -python -o $@ $<

# Generate the single wrapper interface file for the module by creating a file that %includes the individual .i files
$(SwigHeaderDir)/$(PyModuleName).i : $(SourcesToWrap:%.i=$(SwigHeaderDir)/%.i)
	$(SwigHeaderDir)/makePackageInterface.sh $(PyModuleName).i $(SourcesToWrap)	
	mv $(PyModuleName).i $@

# Dummy rule - nothing automatically generates the .i files
$(SourcesToWrap:%.i=$(SwigHeaderDir)/%.i) :

# Compile the wrapper to an object file
$(SwigLibDir)/$(PyModuleName)_wrap.o : $(SwigDir)/common/$(PyModuleName)_wrap.cc
	$(CXX) -c -fPIC -o $@ $^ -I$(PythonIncDir) $(IncludeDirs:%=-I%)

Syntax is clear as a bell, isn't it...

[aidanjt]

Makefiles are easy. You should try GNU autotools for size, now there's a way to spoil/soil your brain.

[Fraz]

Makefiles are easy.

I disagree, but it depends how often you have to write them, like I say. Last time I wrote a Makefile was about 2 years ago, and now when I look at one it makes me wince. The only language I can think of that is more ugly is Perl.

[aidanjt]

M4 is easily considerably more hideous than both.

[Steve]

In the end I split it into two projects.

So now I have a nice shared object and a program that uses it

And all without mangling any makefiles.

[Steve]

The only language I can think of that is more ugly is Perl.

Yeah, but imagine if Larry Wall had invented Makefiles...