ADL®

Value Extractor Block

The Value Extractor Block is commonly used to take a snapshot of information that may be constantly changing in the market, such as the bid quantity of a given instrument. By taking a snapshot, the user can capture the information at a single moment in time and use the "frozen" information later on even if the market continues to change. However, when a new discrete event message triggers the Value Extractor block, the block will replace the old snapshot with a new one.

The Value Extractor Block works as follows:

  1. An incoming discrete event message triggers the Value Extractor block.
  2. When triggered, the Value Extractor Block takes a "snapshot" of the desired information. You can choose to take a snapshot of information contained within the input message or of information unrelated to the message.
  3. After taking the snapshot, the Value Extractor Block passes the input message unchanged through its lower-right port and starts to output the snapshot through the upper-right port.

    As indicated by the yellow output port, the value can be a Numeric, True/False or an Instrument type depending on the type of information captured by the snapshot.

The Value Extractor Block can also be used as a "toggle" to indicate the occurrence of a specific event in the market. To do this, the user can instruct a Value Extractor Block to take a snapshot of the numeric value "1" (in the internal logic canvas, drag and drop the "#" icon onto the canvas and input the value "1") when triggered by a discrete event message. Before the discrete event message occurs, the Value Extractor bBlock will output the default value of zero. However, when the discrete event message occurs, the Value Extractor Block will output a value of 1, indicating that the discrete event has occurred.

Block settings

To change default block settings, double-click the block to open the Block Editor.

Setting Description
Name Name to display beneath the block on the ADL canvas
BodyColor Background color of the block
Formula

Equation used to calculate the value of the block

If not yet defined, the field displays a Click to edit formula link that opens the Formula Builder.

Description Optional text to explain how the block is used