.. -*- coding: utf-8 -*-

Selectors
`````````

A selector is responsible to score how well an object may be used with a
given result set during publishing time selection. This enables the selection
of the most appropriate views to a given result set.

A selector is a method that computes a score. This score is used by
`CubicWeb` engine to identify which view is the best to apply in the
context. In the case, no score is higher than the others, then an
exception is raised ``NoSelectableObject`` to let you know that the
engine was not able to identify the view to apply. In such case
you would need to review your design and make sure your views are
properly defined.

`CubicWeb` provides its own set of selectors that you can use and here
is a description of some of the most common used:

*yes_selector*
    This selector accepts everything which basically means to any result
    set.

*norset_selector*
    This selector accepts no result set, so it can be applied to any
    object.

*rset_selector*
    This selector accepts result set, whatever the number of objects
    in the result set.

*anyrset_selector*
    This selector accepts any non empty result set.

*emptyrset_selector*
    This selector accepts empty result set.

*onelinerset_selector*
    This selector accepts result set with a single line of result.

*twolinerset_selector*
    This selector accepts result set with *at least* two lines of result.

*anonymous_selector*
    This selector accepts if user is anonymous.

*not_anonymous_selector*
    This selector accepta if user is authenticated.


Of course you can write your own set of selectors as you get familiar with the
framework.