def test_create_delete():
"""Make sure we can create, fetch and delete config vars
"""
reg = ComponentRegistry()
reg.set_config('test1', 'hello')
val = reg.get_config('test1')
assert val == 'hello'
reg.set_config('test1', 'hello2')
val = reg.get_config('test1')
assert val == 'hello2'
reg.clear_config('test1')
with pytest.raises(ArgumentError):
reg.get_config('test1')
class ConfigManager(object):
"""A class for managing typed configuration variables
ConfigManager can be used to querying which config variables are defined
and to set or get the currently defined variables.
"""
def __init__(self):
self._known_variables = {}
self._load_providers()
self._load_functions()
self._reg = ComponentRegistry()
def _load_providers(self):
"""Load all config_variables providers using pkg_resources
"""
reg = ComponentRegistry()
for name, provider in reg.load_extensions('iotile.config_variables'):
try:
prefix, conf_vars = provider()
except (ValueError, TypeError) as exc:
raise ExternalError("Error loading config variables",
package=name,
error=str(exc))
for var in conf_vars:
if len(var) != 3 and len(var) != 4:
raise ExternalError(
"Error loading config variable, invalid length",
data=var,
package=name)
name = prefix + ':' + var[0]
if len(var) == 3:
var_obj = ConfigVariable(var[0], var[1], var[2], MISSING)
else:
var_obj = ConfigVariable(name, var[1], var[2], var[3])
if name in self._known_variables:
raise ExternalError(
"The same config variable was defined twice",
name=name)
self._known_variables[name] = var_obj
def _load_functions(self):
"""Load all config functions that should be bound to this ConfigManager
Config functions allow you to add functions that will appear under ConfigManager
but call your specified function. This is useful for adding complex configuration
behavior that is callable from the iotile command line tool
"""
reg = ComponentRegistry()
for _, conf_func in reg.load_extensions('iotile.config_function'):
try:
name = conf_func.__name__
self.add_function(name, conf_func)
except (ValueError, TypeError) as exc:
raise ExternalError("Error loading config function",
name=name,
error=str(exc))
def _format_variable(self, name, var):
"""Format a helpful string describing a config variable
Args:
name (string): The prefixed name of the config variable
var (ConfigVariable): the variable to format
Returns:
string: The formatted string in the form name (type): (default %s) description
"""
if var.default is MISSING:
return "%s (%s): %s [no default]" % (name, var.type,
var.description)
return "%s (%s): %s [default: %s]" % (name, var.type, var.description,
var.default)
@param("glob", "string", desc="Glob pattern for finding config variables")
@return_type("list(string)")
def list(self, glob):
"""List all matching config variables
The glob parameter should be a wildcard expression like:
build:* to find all config variables defined with a build prefix.
Returns:
string[]: A list of string descriptions containing descriptions and
type information.
"""
known_vars = [
x for x in sorted(self._known_variables)
if fnmatch.fnmatchcase(x, glob)
]
return [
'- ' + self._format_variable(x, self._known_variables[x])
for x in known_vars
]
@param("name", "string", desc="Config variable to find")
@stringable
def get(self, name):
"""Get the current value of a config variable
"""
if name not in self._known_variables:
raise ArgumentError("Unknown config variable", name=name)
var = self._known_variables[name]
try:
val = self._reg.get_config(name)
except ArgumentError:
if var.default is not MISSING:
val = var.default
else:
raise ArgumentError(
"Config variable not set and there is no default value",
name=name)
typed_val = type_system.convert_to_type(val, var.type)
return typed_val
@param("name", "string", desc="Config variable to find")
@stringable
def remove(self, name):
"""Remove any currently defined values for the named variable
"""
self._reg.clear_config(name)
@param("name", "string", desc="Config variable to set")
@param("value", "string", desc="Value to set")
def set(self, name, value):
"""Set the current avlue of a config variable
"""
if name not in self._known_variables:
raise ArgumentError("Unknown config variable", name=name)
self._reg.set_config(name, value)
@param("name", "string", desc="Config variable to find")
@return_type("string")
def describe(self, name):
"""Describe a config variable by name
Returns:
string: A short description of what the variable is used for
"""
if name not in self._known_variables:
raise ArgumentError("Unknown config variable", name=name)
var = self._known_variables[name]
return self._format_variable(name, var)
def add_variable(self, name, var_type, desc, default=MISSING):
"""Add a temporary variable to the config variable manager
This function is mainly useful for testing since it does not
persistently store information about the variable.
Args:
name (string): The name of the variable
var_type (string): The type of the variable. This should be a type
known to the type_system.
desc (string): The description of what this variable is for
default (string): An optional default value for the variable
"""
self._known_variables[name] = ConfigVariable(name, var_type, desc,
default)
def add_function(self, name, callable):
"""Add a config function to the config variable manager
Config functions are like config variables but are functions
rather than variables. Sometimes you want to expose configuration
but you really need a function to actually do it. For example,
let's say you want to store a github OAUTH token on behalf of a
user. You would like a config function like `link_github` that
walks the user through logging in to github and getting a token
then you would like to save that token into the config manager like
normal.
add_function lets you bind a method to ConfigManager dynamically.
The function should be a normal function with its first argument
as self and it is turned into a bound method on this instance
of config manager.
Args:
name (string): The attribute name for this function
callable (callable): A function with first argument self
that will be bound to this ConfigManager object as
a method.
"""
if hasattr(self, name):
raise ArgumentError(
"Trying to add a Config function with a conflicting name",
name=name)
bound_callable = callable.__get__(self)
setattr(self, name, bound_callable)
