Context manager for unlocking/locking parameters

set_read_only_parm.py

import contextlib


@contextlib.contextmanager
def set_read_only_parm(parm):
    if not isinstance(parm, (hou.Parm, hou.ParmTuple)):
        return
    # Unlock the parm
    parm.lock(False)
    
    # Do user stuff
    try:
        yield parm
    except (hou.OperationFailed, TypeError, AttributeError) as err:
        msg = "Unable to set parameter! {0}".format(err)
        hou.ui.setStatusMessage(msg, hou.severityType.Error)
        pass
    finally:    
        # Lock the parm up
        parm.lock(True)
    
    
# Usage
fileparm = hou.node("/obj/geo1/null1").parm("file")
with set_read_only_parm(fileparm) as parm:
    parm.set("/tmp/test.bgeo")