Why can't scons find my project's source files? - c++

Question

Here's my project on github.
Here's my SConstruct file:
SConscript('main.scons', variant_dir = 'build', duplicate = 0)
Here's my main.scons file:
import sys
import os
import fnmatch
def find_source_files(directory, ext = "cpp"):
matches = []
for root, dirnames, filenames in os.walk(directory):
for filename in fnmatch.filter(filenames, '*.' + ext):
matches.append(os.path.join(root, filename))
return matches
if __name__ == '__main__':
for f in find_source_files('src'):
print f
else:
Program(target = 'main.bin', source = find_source_files('src'))
Here's what I get when I run it:
bitcycle # cypher ~/git/IeiuniumTela $ find $(pwd) -name "*.bin" -or -name "*.o" -exec rm {} \;; scons; find $(pwd) -name "*.bin" -or -name "*.o"
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
scons: building associated VariantDir targets: build
gcc -o build/main.bin
gcc: fatal error: no input files
compilation terminated.
scons: *** [build/main.bin] Error 4
scons: building terminated because of errors.
Here's what happens when I run `python main.scons' to test it:
bitcycle # cypher ~/git/IeiuniumTela $ python main.scons
src/main.cpp
I'm having a hard time understanding why it can't find my source files. Any suggestions or ideas here?
[UPDATE] After getting some good direction from the mailing list, I found that this worked "good enough" for me.
/SConstruct: SConscript('src/main.scons', variant_dir = 'build', duplicate = 0)
/src/main.scons: Program(target = 'main.bin', source = Glob('*.cpp'))
See the github repository for the full source tree. I've also added an empty build directory to the repo for completeness. I find it interesteding that:
a. SCons' version of Glob isn't recursive, in the context of this build tool for discovering source. I would expect that a recursive discovery option is preferred. :(
b. I need to put the scons file in the same directory as the source file (which is annoying).
c. Print statements apparently work, but sys.stdout.write doesn't (from the python module).

Answer 1

Could it be because your main.scons file is already in the src directory, and your find_source_file is actually searching src/src?
It found the source sources for me when I moved the scons files to the top directory.
Update:
Upon investigation, variant_dir sets the working directory to build, so your find_source_files looks for files in build/src and finds nothing. Would be probably better to either call find_source_files from the SConstruct file, or to use VariantDir() inside main.scons instead.

Answer 2

SCons treats relative directory paths differently from Python, so I wouldnt be surprised to see a difference between the test execution and the SCons execution. Typically in SCons everything is relative to the root SConstruct script, or the SConscript script.
Your code appears correct, but how about adding some debugging print statements in find_source_files() to find out exactly what's happening?
Perhaps you plan to use the find_source_files() function more extensively later on, but for the simple case of one source file, it seems like you are over complicating things and you could just use the following in main.scons:
Program(target = 'main.bin', source = 'src/main.cpp')