genshi.template.eval.LenientLookup

Package genshi :: Package template :: Module eval :: Class LenientLookup |

# Class LenientLookup

    object --+
             |
    LookupBase --+
                 |
                LenientLookup

Default variable lookup mechanism for expressions.

When an undefined variable is referenced using this lookup style, the reference evaluates to an instance of the Undefined class:

    >>> expr = Expression('nothing', lookup='lenient')
    >>> undef = expr.evaluate({})
    >>> undef
    <Undefined 'nothing'>

The same will happen when a non-existing attribute or item is accessed on an existing object:

    >>> expr = Expression('something.nil', lookup='lenient')
    >>> expr.evaluate({'something': dict()})
    <Undefined 'nil'>

See the documentation of the Undefined class for details on the behavior of such objects.

See Also: StrictLookup

Instance Methods
Inherited from `object`: `__delattr__`, `__getattribute__`, `__hash__`, `__init__`, `__new__`, `__reduce__`, `__reduce_ex__`, `__repr__`, `__setattr__`, `__str__`

Class Methods
undefined(cls, key, owner=UNDEFINED) Return an `Undefined` object. |
Inherited from `LookupBase`: `globals`, `lookup_attr`, `lookup_item`, `lookup_name`

Properties
Inherited from `object`: `__class__`

Method Details

### undefined(cls, key, owner=UNDEFINED) Class Method |
Return an `Undefined` object. Parameters: `key` - the name of the variable `owner` - the owning object, if the variable is accessed as a member Overrides: LookupBase.undefined