Function

Gtk.TreeIterCompareFunc

Declaration

int
TreeIterCompareFunc (
  GtkTreeModel* model,
  GtkTreeIter* a,
  GtkTreeIter* b,
  gpointer user_data
)

Description [src]

A GtkTreeIterCompareFunc should return a negative integer, zero, or a positive integer if a sorts before b, a sorts with b, or a sorts after b respectively.

If two iters compare as equal, their order in the sorted model is undefined. In order to ensure that the GtkTreeSortable behaves as expected, the GtkTreeIterCompareFunc must define a partial order on the model, i.e. it must be reflexive, antisymmetric and transitive.

For example, if model is a product catalogue, then a compare function for the “price” column could be one which returns price_of(a) - price_of(b).

Parameters

`model`	`GtkTreeModel`
	The `GtkTreeModel` the comparison is within
	Ownership is not transferred to the callee
`a`	`GtkTreeIter`
	A `GtkTreeIter` in `model`
	Ownership is not transferred to the callee
`b`	`GtkTreeIter`
	Another `GtkTreeIter` in `model`
	Ownership is not transferred to the callee
`user_data`	`gpointer`
	Data passed when the compare func is assigned e.g. by `gtk_tree_sortable_set_sort_func()`

Return value

Returns: `int`
a negative integer, zero or a positive integer depending on whether `a` sorts before, with or after `b`