cfg_write

#!/usr/bin/env python3

"""
This program is part of MoaT.
Its job is simply to extract values from a YAML-formatted config file.
"""

import sys
import yaml
from traceback import print_exc
from ordered_yaml import load,dump

def usage():
    print("Usage: {} <file> <some.key value>…".format(sys.argv[0]), file=sys.stderr)
    sys.exit(2)

if len(sys.argv) < 2: usage()
f,*kk = sys.argv[1:]
if not kk or len(kk)%1: usage()

s = load(open(sys.argv[1]))
while kk:
    v = s
    ks = kk.pop(0).split('.')
    lk = ks.pop()
    for k in ks:
        if not isinstance(v,dict):
            raise RuntimeError("Not a dict at {}".format(".".join(ks)))
        if k in v:
            v = v[k]
        else:
            v[k] = {}
            v = v[k]
    if not isinstance(v,dict):
        raise RuntimeError("Not a dict at {}.{}".format(".".join(ks),lk))
    if not isinstance(v.get(lk,""),(str,int,float)):
        raise RuntimeError("Not a scalar value at {}.{}".format(".".join(ks),lk))
    val = kk.pop(0)
    try: val = float(val)
    except ValueError:
        try: val = int(val)
        except ValueError: pass
        else: val = str(val)
    v[lk] = val

dump(s, stream=open(sys.argv[1],'w'), default_flow_style=False)