How to set up MS Visual Studio 2005 project dependencies for efficient compiling (c++)?

Question

How do I set up MS Visual Studio 2005 project dependencies such that making a change in a higher level project does not force a recompile of all other projects it depends on.

If I have 5 dll projects, which are related in various ways... Under the 'Project'->'Dependencies' I have identified the next project down, but only down one level. When I make a small change to the higher project, a select 'Build'->'Build myLib' the lower project is also recompiled... If I specify all dependencies, then all dependent projects are also recompiled... which isn't right, is it?

If I remove the explicit dependency, the lower project won't get rebuilt, even if it should be (which is as i would expect).

What if I have several levels of dependency (A depends on B depends on C etc)?

Answer 1

What if I have several levels of dependency (A depends on B depends on C etc)?

Select project A from the dropdown, add B as a dependency. Similarly, for B, select C as a dependency.

Answer 2

How do I set up MS Visual Studio 2005 project dependencies such that making a change in a higher level project does not force a recompile of all other projects it depends on.

I think you mean:

How do I set up MS Visual Studio 2005 project dependencies such that making a change in a higher level project does not force a recompile of all other projects that depend, possibly indirectly, on it?

I think you are using terms like "higher" and "lower" in the opposite sense than I would -- for a pair of projects, I think of the "lower" project as being the one that depends on the other one. It could be that your "mental diagram" is simply vertically flipped with respect to mine, which is fine; or it could be that you have misinterpreted what the Project Dependencies box is asking for, which is not. It is asking for the list of projects that the named project in the drop-down list above directly depends on, namely those projects that must be up-to-date (which possibly requires rebuilding) before the named project can be built.

So: could you please clarify in what sense you intend "higher" and "lower" to be taken.

What VC++ should (and I'm certain does) do when you ask to build some project X is check whether all projects that X depends on, either directly or indirectly, are up-to-date, and build any that are not. When this building occurs, each project is always built after any projects that it depends on, either directly or indirectly. Note that projects may require rebuilding even if they are not changed themselves -- e.g. if X depends on Y and Y depends on Z, then changing Z and requesting X to be built entails first building Z, then Y (which was not changed), then X. If there are even "lower" (in my sense) projects that depend on X, they will not be built when you request X to be built.

Answer 3

I have my project dependencies set for only level anyway:

• Project A depends on Library B
• Project A depends on Library C

However, library B also uses library C, but I don't have that set as a dependency. This seems to work fine.

Are you changing header files? Certainly - if you change headers, then any project dependent on that header will have to be rebuilt whether you have Project Dependencies set up or not.