Python CSC Electronic Office
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pyceo/ceo/conf.py

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4.3 KiB

"""
Configuration Utility Module
This module contains functions to load and verify very simple configuration
files. Python supports ".ini" files, which suck, so this module is used
instead.
Example Configuration File:
include /path/to/other.cf
# these values are the same:
name_protected = "Michael Spang"
name_unprotected = Michael Spang
# these values are not the same:
yes_no = " yes"
no_yes = yes
# this value is an integer
arbitrary_number=2
# this value is not an integer
arbitrary_string="2"
# this is a key with no value
csclub
# this key contains whitespace
white space = sure, why not
# these two lines are treated as one
long line = first line \\
second line
Resultant Dictionary:
{
'name_protected': 'Michael Spang',
'name_unprotected:' 'Michael Spang',
'yes_no': ' yes',
'no_yes': 'yes',
'arbirary_number': 2,
'arbitrary_string': '2',
'csclub': None,
'white space': 'sure, why not'
'long line': 'first line \\n second line'
... (data from other.cf) ...
}
"""
from curses.ascii import isspace
class ConfigurationException(Exception):
"""Exception class for incomplete and incorrect configurations."""
def read(filename, included=None):
"""
Function to read a configuration file into a dictionary.
Parmaeters:
filename - the file to read
included - files previously read (internal)
Exceptions:
IOError - when the configuration file cannot be read
"""
if not included:
included = []
if filename in included:
return {}
included.append(filename)
conffile = open(filename)
options = {}
while True:
line = conffile.readline()
if line == '':
break
# remove comments
if '#' in line:
line = line[:line.find('#')]
# combine lines when the newline is escaped with \
while len(line) > 1 and line[-2] == '\\':
line = line[:-2] + line[-1]
next = conffile.readline()
line += next
if next == '':
break
line = line.strip()
# process include statements
if line.find("include") == 0 and isspace(line[7]):
filename = line[8:].strip()
options.update(read(filename, included))
continue
# split 'key = value' into key and value and strip results
pair = map(str.strip, line.split('=', 1))
# found key and value
if len(pair) == 2:
key, val = pair
# found quoted string?
if val and val[0] == val[-1] == '"':
val = val[1:-1]
# unquoted, found num?
elif val:
try:
if "." in val:
val = float(val)
elif val[0] == '0':
val = int(val, 8)
else:
val = int(val)
except ValueError:
pass
# save key and value
options[key] = val
# found only key, value = None
elif len(pair[0]) > 1:
key = pair[0]
options[key] = None
return options
def check_string_fields(filename, field_list, cfg):
"""Function to verify thatfields are strings."""
for field in field_list:
if field not in cfg or type(cfg[field]) is not str:
raise ConfigurationException('expected string value for option "%s" in "%s"' % (field, filename))
def check_integer_fields(filename, field_list, cfg):
"""Function to verify that fields are integers."""
for field in field_list:
if field not in cfg or type(cfg[field]) not in (int, long):
raise ConfigurationException('expected numeric value for option "%s" in "%s"' % (field, filename))
def check_float_fields(filename, field_list, cfg):
"""Function to verify that fields are integers or floats."""
for field in field_list:
if field not in cfg or type(cfg[field]) not in (float, long, int):
raise ConfigurationException('expected float value for option "%s" in "%s"' % (field, filename))