Command Line Options

Suppose, for example, we want to us the Test-Driven-Development (TDD) testing framework such as doctest. For this, we would like to be able to use two different build configurations:

• Normal (Debug) build
• Test (doctest) build

Setting up CLI choices

There a couple of different approaches, depending on you specifics needs. The two major options are:

• Command Line Variables
• Command Line Flags

Command Line Variables

Suppose we require two build opions:

1. A Debug build (default)
2. A Test build

First, we to create a Variables object to hold out options, e.g.

vars = Variables()

We Add the options we require to the variables object and that object to our environment, e.g.

vars.Add(EnumVariable('BUILD_TYPE', 'type of build to use', 'debug', allowed_values=('debug', 'test')))
env = Environment(variables = vars)

Then, within the SConstruct file we can test against the supplied CLI variable, e.g. (in this example, the default option has been set to debug)

if env['BUILD_TYPE'] == 'debug':
    print '*** Debug build'

if env['BUILD_TYPE'] == 'tdd':
    print '*** TDD build'
    env.Append( CPPPATH=["#/doctest/doctest"] )
    env.Append( CPPDEFINES = ['TDD'] )

To test, run scons, i.e.

$ scons
scons: Reading SConscript files ...
*** Debug build
scons: done reading SConscript files.
scons: Building targets ...
...

and to check the Test option:

$ scons BUILD_TYPE=test
scons: Reading SConscript files ...
*** Test build
scons: done reading SConscript files.
scons: Building targets ...
...

There is also an option to automatically generates the scons help capability for our project using Help(vars.GenerateHelpText(env)) , e.g.

vars.Add(EnumVariable('BUILD_TYPE', 'type of build to use', 'debug', allowed_values=('debug', 'test')))
env = Environment(variables = vars)
Help(vars.GenerateHelpText(env))

Running scons with the -h option invokes the help text:

$ scons -h
scons: Reading SConscript files ...
*** debug build
scons: done reading SConscript files.

BUILD_TYPE: type of build to use (debug|test)
    default: debug
    actual: debug

Option 2 - Simple flag

Another approach is to use Values of variables passed to the SConscript file(s):

scons debug=1 .

These variables are available in SConscript files through the ARGUMENTS dictionary, and can be used in the SConscript file(s) to modify the build in any way:

if ARGUMENTS.get('debug', 0):
    env = Environment(CCFLAGS = '-g')
else:
    env = Environment()