Cmd / Cmds: Add config file support

An application based on Cmds will now try to read StringTree
formatted config data from a file $HOME/.<name>rc, and make the data
available via the newly added conf_value() method.

Signed-off-by: Jan Lindemann <jan@janware.com>

tools/python/jwutils/Cmds.py

@@ -3,9 +3,11 @@
 from typing import Optional
 import os, sys, argcomplete, argparse, importlib, inspect, re, pickle, asyncio, cProfile
 from argparse import ArgumentParser
+from pathlib import Path, PurePath
 
 import jwutils
 from jwutils.log import *
+from jwutils.stree import serdes
 
 class Cmds: # export
 
@@ -30,10 +32,19 @@ class Cmds: # export
             for sub_cmd in cmd.children:
                 self.__add_cmd_to_parser(sub_cmd, subparsers)
 
+    def __parse_config(self):
+        exe_stem = str(PurePath(sys.argv[0]).stem)
+        path = str(Path.home()) + '/.' + exe_stem + 'rc'
+        if not os.path.exists(path):
+            return None, []
+        slog(DEBUG, 'Reading configuration "{}"'.format(path))
+        return serdes.read(path, ''), [path]
+
     def __init__(self, description: str = '', filter: str = '^Cmd.*', modules: None=None, eloop: None=None) -> None:
         self.__description = description
         self.__filter = filter
         self.__modules = modules
+        self.__conf, self.__conf_paths = self.__parse_config()
         self.__cmds = []
         self.eloop = eloop
         self.__own_eloop = False
@@ -43,6 +54,7 @@ class Cmds: # export
 
         log_level = "notice"
         log_flags = 'stderr,position,prio,color'
+        log_file = None
         # poor man's parsing in the absence of a complete command-line definition
         for i in range(1, len(sys.argv)):
             if i >= len(sys.argv) - 1:
@@ -64,6 +76,7 @@ class Cmds: # export
         self.__parser.add_argument('--log-level', help='Log level', default=log_level)
         self.__parser.add_argument('--backtrace', help='Show exception backtraces', action='store_true', default=False)
         self.__parser.add_argument('--write-profile', help='Profile code and store output to file', default=None)
+        self.__parser.add_argument('--log-file', help='Log file', default=log_file)
         if self.__modules == None:
             self.__modules = [ '__main__' ]
         subcmds = set()
@@ -118,6 +131,11 @@ class Cmds: # export
         if pr is not None:
             pr.enable()
 
+        if self.__conf:
+            self.__conf.dump(DEBUG, "Configuration")
+        if self.args.log_file is not None:
+            add_log_file(self.args.log_file)
+
         try:
             ret = await self._run(self.args)
         except Exception as e:
@@ -144,6 +162,12 @@ class Cmds: # export
                 self.eloop = None
             self.__own_eloop = False
 
+    def conf_value(self, path, default=None):
+        ret = None if self.__conf is None else self.__conf.value(path)
+        if ret is None and default is not None:
+            return default
+        return ret
+
     def parser(self) -> ArgumentParser:
         return self.__parser