validation fails - file transform source cannot be resolved

[p0las]

why is the validation failing in this case? what am I missing?

import os
import PyOpenColorIO as OCIO

os.environ['SHOT_CDL_PATH'] = 'c:/temp/a.cdl'
os.environ['SHOT_LUT_PATH'] = 'c:/temp/a.lut'

config = OCIO.Config.CreateRaw()

config.addSearchPath('search_path')

config.addEnvironmentVar('SHOT_CDL_PATH', '${SHOT_CDL_PATH}')
config.addEnvironmentVar('SHOT_LUT_PATH', '${SHOT_LUT_PATH}')

config.addColorSpace(OCIO.ColorSpace(name='foobar', family="Project", bitDepth=OCIO.BIT_DEPTH_F32, isData=False,
            description='test', allocation=OCIO.ALLOCATION_UNIFORM, allocationVars=[-0.249136, 1.468],
            fromReference=OCIO.GroupTransform([
                OCIO.FileTransform(src='${SHOT_CDL_PATH}', cccId='0', direction=OCIO.TransformDirection.TRANSFORM_DIR_FORWARD),
                OCIO.FileTransform(src='${SHOT_LUT_PATH}', interpolation=OCIO.Interpolation.INTERP_TETRAHEDRAL, direction=OCIO.TransformDirection.TRANSFORM_DIR_FORWARD)
            ])
        ))

config.validate()

it fails to resolve the env var for some reason: Exception: Config failed validation expanding file transform paths. The file transform source cannot be resolved: '${SHOT_CDL_PATH}'.

[p0las]

It looks like when config.addEnvironmentVar is called, the internal environment variable lookup is reset with the default value provided (here the syntax to indicate none), so that later validate call can’t see the original value assigned with os.environ. You could do this before calling validate to refresh the lookup map:

config.setEnvironmentMode(OCIO.ENV_ENVIRONMENT_LOAD_PREDEFINED)
config.loadEnvironment()