How to use SCONS/CPPPATH: Source not found

Question

I am using Scons/Sconstruct to build a project with the following directory structure:

+A
|--A1
|--A2
+B
|--B1
  |-b1.cpp

The 'A' directory contains code which a sconstruct file in B1 refers to, as per the following scontruct file (simplified for use here):

env = Environment(CPPPATH=['.', '../../']
source_common = 'A/A1/source.cpp'
env.Program( target = 'b1_exec', source = ['b1.cpp', source_common] )

However, when compiling, I receive an error that the A/A1/source.cpp cannot be found. I would have thought adding the CPPPATH parameter would have allowed the compiler to find the source.cpp file. I seem to be going round in circles, so would very much appreciate any help.

Thanks.

Answer 1

One of the first rules to remember when building with SCons is that the source code to be built must be in the same directory/sub-directory as the root level SConstruct script. There are a few options you could consider:

1. Place the SConstruct at the root directory of A and B, which would control the building of both sub-directories.

2. Make each directory (A and B) be separate projects and each would have its own SConstruct. Then project B would refer to libraries built separately in project A.

The choice just depends on the nature of the projects and your requirements. A downside to option 2 is that if a source file in A1 or A2 changes, it wont be detected when compiling project B, since project B will only know about the libraries/headers in project A.

Regarding the CPPPATH construction variable: this variable configures the location of the header files. If this project were on Linux (or other Unix variants) with the gcc/g++ compiler, then the CPPPATH variable configures the '-I' compiler flags. Remember, when setting the CPPPATH variable, its not necessary to include the '-I' flag, SCons will add it in a platform-independently manner (meaning it will set it based on the platform and compiler being used).