A minimal example of detecting if the DUNE DAQ environment contains ND or FD components.

check_nd_fd.py

#!/bin/env python

import subprocess
import sys

def check_spack_pkg(pkg):
    completed_process = subprocess.run(f"spack find --loaded {pkg}",
                                       shell=True, check=False,
                                       stdout=subprocess.DEVNULL,
                                       stderr=subprocess.DEVNULL)
    print(f"checking if '{pkg}' is a loaded spack module") # To-be-removed
    if completed_process.returncode == 0:
        return True
    elif completed_process.returncode == 1:
        return False
    else:
        print("spack command is not avaliable. Make sure you are in DUNE DAQ development/running environment.")
        sys.exit(1)

class DAQRelease:
    _isND = None
    _isFD = None

    @classmethod
    def isND(self):
        if self._isND is None:
            if check_spack_pkg("ndreadoutlibs"):
                self._isND = True
            else:
                self._isND = False
        return self._isND

    @classmethod
    def isFD(self):
        if self._isFD is None:
            if check_spack_pkg("fdreadoutlibs"):
                self._isFD = True
            else:
                self._isFD = False
        return self._isFD

if DAQRelease.isND():
    print("import ND DAQ modules")
    # import <nd_module_1>
    # import <nd_module_2>
else:
    print("Not in ND DAQ environment.")

if DAQRelease.isFD():
    print("import FD DAQ modules")
    # import <fd_module_1>
    # import <fd_module_2>
else:
    print("Not in FD DAQ environment.")

if DAQRelease.isND():
    print("calling ND module")
    # nd_module_1.class2()

if DAQRelease.isFD():
    print("calling FD module")
    # fd_module_1.class2()

Line 11 was for illustration only. and should be commented out. I put it there just to verify that the calling of spack command is done only once for ND or FD.

Note that this only works with the new nightlies since N23-06-23 (NFD23-06-23 and NND23-06-23).

While testing this script, I found that I did not move ndreadoutlibs, fdreadoutlibs and a few other packages out of the base release into ND or FD release. It was a temporary measure put in place before Roland and I completed the splitting of readoutmodules.

Alternatively, python 3.6 and later has a "ModuleNotFoundError" exception (we use 3.10.4 in DAQ). So it you prefer the pure python approach, you can do:

# at the top of the python script where the "import" statements are placed
try:
    import <nd_module_1>
    import <nd_module_2>
except ModuleNotFoundError:
    notND = True
    pass

try:
    import <fd_module_1>
    import <fd_module_2>
except ModuleNotFoundError:
    notFD = True
    pass

# encapsulate the usage of ND or FD modules' functionalities with if statements on the condition of the "notND" and "notFD" flags. 
if not notND:
    nd_module_1.class2.()

if not notFD:
    fd_module_1.class2.()