~mdw / chopwood / blame
| Commit | Line | Data |
|---|---|---|
| a2916c06 MW |
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 | |
| 9fc9351d | 29 | import output as O; OUT = O.OUT |
| a2916c06 MW |
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. | |
| 9fc9351d MW |
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)) | |
| a2916c06 MW |
91 | |
| 92 | ## Run the hooks. | |
| 93 | for func in _HOOKS: | |
| 94 | func() | |
| 95 | ||
| 96 | ###----- That's all, folks -------------------------------------------------- |