Is it possible to have identically named source files in one visual studio c++ project?

Question

I'm working on a static library project for a c++ course I'm taking. The teacher insists that we define only one function per source file, grouping files/functions belonging to the same class in subdirectories for each class. This results in a structure like:

MyClass
    \MyClass.cc (constructor)
    \functionForMyClass.cc
    \anotherFunctionForMyClass.cc 
OtherClass
    \OtherClass.cc (constructor)

Whether this is good practice or not is something I'd not like to discuss, since I'm simply obliged to organize my project in this manner.

I'm working in visual studio 2008, and somehow got strange link errors when using an identically named function (and thus filename) in two classes. This appears to be caused by the fact that visual studio puts all .obj files (one for each source file) in one intermediate directory, overwriting earlier generated object files when compiling identically named source files.

This could be solved by putting the object files in subdirectories based on the relative path of the input file. Visual studio allows one to configure the names of object files it generates and has macros to use in there, but there appears to be no macro for 'relative path of input file'.

So, is there some way to get this to work? If not, is using one project for each class the best work-around?

Answer 1

You can also change output file name per file in its properties. Just make sure you use different names.

Answer 2

I can't think of any way to fudge the project settings to get VStudio to automatically split out the intermediate files into separate folders.

You have a few chances -

1. Build the class name into each file name. Most IDE's display just the file name in the tab view so if you do have several methods in different classes with the same name, its going to be difficult to tell them apart if the file name does not include the class name along with the method name. Which is really why I think your teachers advice is madness. I have not seen any programming style guide advocating that approach. Additionally it goes directly against the way various tools work - if you use Visual Studio to create a class, it creates one cpp file and one header, and automatically appends each new function to the single cpp file.

2. You could create a static library per class. When linking in static libs the obj files are all packaged up inside the .lib so conflicts are no longer a problem.

3. Switch comp-sci courses to one thats not being taught by a nut job. Seriously, this guy is completely out of touch with industry best practices and is trying to impose their own weird ideas on their students: Ideas that are going to have to be unlearnt the moment they leave the teaching environment.

Answer 3

Can you use the class name in the filename to disambiguate? I'm thinking that you might have

MyClass \MyClass.cc (constructor) \function1_MyClass.cc \function2_MyClass.cc

That would mean that every file would have a unique-enough name to defeat the problem. Is that an acceptable strategy?

Answer 4

You are right, by default all object files are put into the same directory and their filenames are based on the source file name. The only solution I can think of is to change conflicting file's output file path in here:

PS. It sounds like the lecturer has a crappy (probably written by the lecturer himself) automatic code verifier that imposes this restriction. To get extra marks, offer to rewrite the parser so it works with normal/sane/non-weird projet layout.

Answer 5

You don't have to put them in different translation units... why not put each function in a .h and include them all in one .cc per class? That will very likely give better output from the compiler.

I'd be asking why the teacher is insisting on this odd structure, too, the reasoning behind it should be explained. I know you didn't ask that of us, so that's all I'll say.

Answer 6

You could probably arrange the properties of the project to put the object files into a folder which is below the folder of each source file. Once the project has this property, then every source file should inherit this property. (But if you've done experiments like Igor has suggested, then you may need to go through the properties as reset them back to the parent).

Having looked at the help files, I think you should go to project properties/C C++/Outpuf Files/Object File Name: and enter $(InputDir) (no trailing backslash). Every source file should then inherit this property and your .obj files should be separated.

You may need to do a Clean Solution before you make any changes.

Answer 7

• Renaming the object files will work, but it's going to be a pain, and it will slow your compile/link cycle down. I've never figured out why, but it seems to confuse Visual Studio if the object files don't have the default names.

• You could prefix the funciton name with the class name; e.g. myclass-ctor.cc, myclass-function1.cc etc.

• You could have one .cc file per class which #includes the individual function files. In this case you'll need to prevent the #included files from being compiled seperately (either rename their extension or set Properties->Exclude From Build to 'Yes').

Out of curiosity, where does your teacher want you to put free functions e.g. local helper functions that might normally belong in an anonymous namespace?

If not, is using one project for each class the best work-around?

Not a good idea - apart from the fact that you won't end up with a single static library (without even more jiggery pokery), your link times are likely to increase and it will hide a lot of pertinent info from the optimizer.

On another note; If the course is actually about C++ not OO programming, do what you need to pass but take your teacher's advice with a pinch of salt.