gdk:content-provider-new-union (&rest providers)

providers -- a list of gdk:content-provider objects

The new gdk:content-provider object representing the union of the given providers.

Creates a content provider that represents all the given providers. Whenever data needs to be written, the union provider will try the given providers in the given order and the first one supporting a format will be chosen to provide it. This allows an easy way to support providing data in different formats. For example, an image may be provided by its file and by the image contents with a call such as

(g:with-values ((gitem "BibItem" item)
                (gstring "gchararray" (item-key item)))
  (gdk:content-provider-new-union
      (gdk:content-provider-new-for-value gitem)
      (gdk:content-provider-new-for-value gstring))
  ...)