scons emitter

import SCons
import os

def infoBuilder(target, source, env):
    print '<<< Printing info >>>'


FILE_CONTENT= \
r'''
const char * const CfgString = "{}";
'''

def generateAction(source, target, env):
    lines = []
    print 'source=' + str(source[0])
    with open(str(source[0])) as f:
        for line in f:
            line = line.strip()
            if line:
                lines.append(line)
    assert lines
    if not os.path.exists('gen'):
        os.makedirs('gen')
    with open('gen/Cfg.c', 'w') as f:
        f.write(FILE_CONTENT.format(lines[0]))
    env.SideEffect('gen/Cfg.c', target)
    with open(str(target[0]), 'w') as f:
        f.write('')

def genEmitter(target, source, env):
    print 'genEmitter trg:{}'.format(target[0])
    from glob import glob
    for cPath in glob('gen/*.c'):
        oPath = 'obj/' + os.path.splitext(os.path.basename(cPath))[0] + '.o'
        obj = env.Object(target=oPath, source=cPath)
        print 'obj=' + str(obj)
        # env.Depends('prg', obj)
        source.append(obj)
    return target, source


def linkerAction(target, source, env):
    print 'linkerAction'
    sources = [str(src) for src in source]
    cmd = 'gcc -o {} {}'.format(target[0], ' '.join(sources))
    print cmd
    return os.system(cmd)


def createRules():
    linker = Builder(action=linkerAction, emitter=genEmitter)
    env = Environment(
        BUILDERS={'Linker': linker},
        CXXFLAGS='-O2 -Wall')
    mainObj = env.Object('obj/main.o', 'src/main.c')
    prg = env.Linker('prg', mainObj)  #emitter=genEmitter here doesn't work
    genReady = env.File('gen/genReady')
    env.Command(target=genReady, source='cfg/sample.cfg', action=generateAction)
    env.AlwaysBuild(env.Alias(target='INFO2', action=infoBuilder))
    env.AlwaysBuild(env.Alias(target='INFO', action=infoBuilder))
    env.AlwaysBuild(env.Alias(target='all', source=('INFO', genReady, prg)))
    env.Default('all')


createRules()