# ConfigItem¶

class astropy.config.ConfigItem(defaultvalue='', description=None, cfgtype=None, module=None, aliases=None)[source]

Bases: object

A setting and associated value stored in a configuration file.

These objects should be created as members of ConfigNamespace subclasses, for example:

class _Conf(config.ConfigNamespace):
unicode_output = config.ConfigItem(
False,
'Use Unicode characters when outputting values, and writing widgets '
'to the console.')
conf = _Conf()

Parameters
defaultvalueobject, optional

The default value for this item. If this is a list of strings, this item will be interpreted as an ‘options’ value - this item must be one of those values, and the first in the list will be taken as the default value.

descriptionstr or None, optional

A description of this item (will be shown as a comment in the configuration file)

cfgtypestr or None, optional

A type specifier like those used as the values of a particular key in a configspec file of configobj. If None, the type will be inferred from the default value.

modulestr or None, optional

The full module name that this item is associated with. The first element (e.g. ‘astropy’ if this is ‘astropy.config.configuration’) will be used to determine the name of the configuration file, while the remaining items determine the section. If None, the package will be inferred from the package within which this object’s initializer is called.

aliasesstr, or list of str, optional

The deprecated location(s) of this configuration item. If the config item is not found at the new location, it will be searched for at all of the old locations.

Raises
RuntimeError

If module is None, but the module this item is created from cannot be determined.

Attributes Summary

 cfgtype A type specifier like those used as the values of a particular key in a configspec file of configobj. rootname Rootname sets the base path for all config files.

Methods Summary

 Returns the value of this ConfigItem Reloads the value of this ConfigItem from the relevant configuration file. set(value) Sets the current value of this ConfigItem. set_temp(value) Sets this item to a specified value only inside a with block.

Attributes Documentation

cfgtype = None

A type specifier like those used as the values of a particular key in a configspec file of configobj.

rootname = 'astropy'

Rootname sets the base path for all config files.

Methods Documentation

__call__()[source]

Returns the value of this ConfigItem

Returns
val

This item’s value, with a type determined by the cfgtype attribute.

Raises
TypeError

If the configuration value as stored is not this item’s type.

reload()[source]

Reloads the value of this ConfigItem from the relevant configuration file.

Returns
val

The new value loaded from the configuration file.

set(value)[source]

Sets the current value of this ConfigItem.

This also updates the comments that give the description and type information.

Parameters
value

The value this item should be set to.

Raises
TypeError

If the provided value is not valid for this ConfigItem.

set_temp(value)[source]

Sets this item to a specified value only inside a with block.

Use as:

ITEM = ConfigItem('ITEM', 'default', 'description')

with ITEM.set_temp('newval'):
#... do something that wants ITEM's value to be 'newval' ...
print(ITEM)

# ITEM is now 'default' after the with block

Parameters
value

The value to set this item to inside the with block.