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<arrow> ( model quot -- arrow )

Vocabulary
models.arrow

Class description
Arrow model values are computed by applying a quotation to the value of another model. Arrows are automatically updated when the underlying model changes. Arrows are constructed by <arrow>.

Examples
The following code displays a label showing the result of applying sq to the value 5:

USING: models models.arrow math.parser ui.gadgets.labels ui.gadgets.panes ; 5 <model> [ sq ] <arrow> [ number>string ] <arrow> <label-control> gadget.

An exercise for the reader is to keep the original model around on the stack, and change its value to 6, observing that the label will immediately display 36.

Definition

USING: models ;

IN: models.arrow

TUPLE: arrow < model quot ;

Methods

USING: accessors kernel models models.arrow sequences ;

M: arrow model-activated
    [ dependencies>> ] keep [ model-changed ] curry each ;


USING: kernel models models.arrow ;

M: arrow model-changed
    [ compute-arrow-value ] [ set-model ] bi ;