Support for getters?

[qria]

Common pattern for optional property is to use .get:

class MyConfig(Configuration):
    my_name = config_property('my_name', str)

config = MyConfig({'my_name': 'myname'})

print('hello %s' % (config.my_name or 'anonymous'))  # hello myname
print('hello %s' % config.get('my_name', 'anonymous'))  # hello myname

Unfortunately currently this fails silently in some cases.

class MyConfig(Configuration):
    my_name = config_property('my_name', str, default='defaultname')

config = MyConfig()

print('hello %s' % (config.my_name or 'anonymous'))  # hello defaultname
print('hello %s' % config.get('my_name', 'anonymous'))  # hello anonymous

class MyConfig(Configuration):
    my_name = config_property('myinfo.name', str)

config = MyConfig({'myinfo': {'name': 'myname', 'age': 10, 'gender': 'male'}})

print('hello %s' % (config.my_name or 'anonymous'))  # hello myname
print('hello %s' % config.get('my_name', 'anonymous'))  # hello anonymous

I am not sure whether or not settei intends to support getters,

but I think it would be nice if settei supported getters or explicitly raise an error.

[dahlia]

If you don't set any default/default_func for a config_property it will raise KeyError on lack of value.

.get() is a part of collections.Mapping protocol (dictionary-like interface).