| 1 | ### -*-python-*- |
| 2 | ### |
| 3 | ### Configuration handling |
| 4 | ### |
| 5 | ### (c) 2013 Mark Wooding |
| 6 | ### |
| 7 | |
| 8 | ###----- Licensing notice --------------------------------------------------- |
| 9 | ### |
| 10 | ### This file is part of Chopwood: a password-changing service. |
| 11 | ### |
| 12 | ### Chopwood is free software; you can redistribute it and/or modify |
| 13 | ### it under the terms of the GNU Affero General Public License as |
| 14 | ### published by the Free Software Foundation; either version 3 of the |
| 15 | ### License, or (at your option) any later version. |
| 16 | ### |
| 17 | ### Chopwood is distributed in the hope that it will be useful, |
| 18 | ### but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | ### MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | ### GNU Affero General Public License for more details. |
| 21 | ### |
| 22 | ### You should have received a copy of the GNU Affero General Public |
| 23 | ### License along with Chopwood; if not, see |
| 24 | ### <http://www.gnu.org/licenses/>. |
| 25 | |
| 26 | from __future__ import with_statement |
| 27 | |
| 28 | import os as OS; ENV = OS.environ |
| 29 | import output as O; OUT = O.OUT |
| 30 | import sys as SYS |
| 31 | import types as TY |
| 32 | |
| 33 | from auto import PACKAGE, VERSION |
| 34 | |
| 35 | ### Configuration is done by interpreting a file of Python code. We expect |
| 36 | ### the code to define a number of variables in its global scope. We import |
| 37 | ### a number of identifiers (named in the `EXPORT' list) to this module, and |
| 38 | ### also our entire parent module as `chpwd'. |
| 39 | |
| 40 | ## Names which ought to be exported to the configuration module. |
| 41 | _EXPORT = {} |
| 42 | |
| 43 | ## The configuration module. |
| 44 | CFG = TY.ModuleType('chpwd_config') |
| 45 | |
| 46 | ## A list of hooks to call once configuration is complete. |
| 47 | _HOOKS = [] |
| 48 | def hook(func): |
| 49 | """Decorator for post-configuration hooks.""" |
| 50 | _HOOKS.append(func) |
| 51 | return func |
| 52 | |
| 53 | ## A suitable set of defaults. |
| 54 | DEFAULTS = {} |
| 55 | |
| 56 | def export(*names, **kw): |
| 57 | """ |
| 58 | Export the names to the configuration module from the caller's environment. |
| 59 | """ |
| 60 | |
| 61 | ## Find the caller's global environment. Please don't try this at home. |
| 62 | try: raise Exception |
| 63 | except: tb = SYS.exc_info()[2] |
| 64 | env = tb.tb_frame.f_back.f_globals |
| 65 | |
| 66 | ## Export things. |
| 67 | for name in names: |
| 68 | _EXPORT[name] = env[name] |
| 69 | _EXPORT.update(kw) |
| 70 | |
| 71 | ## Some things to export for sure. |
| 72 | export('PACKAGE', 'VERSION', 'ENV', CONF = SYS.modules[__name__]) |
| 73 | |
| 74 | def loadconfig(config): |
| 75 | """ |
| 76 | Load the configuration, populating the `CFG' module with settings. |
| 77 | """ |
| 78 | |
| 79 | ## Make a new module for the configuration, and import ourselves into it. |
| 80 | d = CFG.__dict__ |
| 81 | d.update(_EXPORT) |
| 82 | d.update(DEFAULTS) |
| 83 | |
| 84 | ## And run the configuration code. |
| 85 | try: |
| 86 | with open(config) as f: |
| 87 | exec f in d |
| 88 | except IOError, e: |
| 89 | OUT.warn("couldn't open configuration file `%s': %s" % |
| 90 | (config, e.strerror)) |
| 91 | |
| 92 | ## Run the hooks. |
| 93 | for func in _HOOKS: |
| 94 | func() |
| 95 | |
| 96 | ###----- That's all, folks -------------------------------------------------- |