tick()

tock()

callback(void* Address)

Remarks:

• The tick function runs in irregular intervals dependent on market activity. The more assets are traded, the more quotes will trigger a tick run. The tick function normally executes much more frequently than the run function, but can also execute less often when few quotes are received, f.i. after market hours. The minimum time between two tick calls can be set up with TickTime. If a new quote arrives earlier, it is delayed until the TickTime is over.
• Within a tick function the asset name, the current ask price, and the current ask-bid spread can be evaluated with the Asset string, with priceClose(0), and with the Spread variable. The time stamp of the last quote is returned by seconds(0) or wdate(0). Date/time functions inside tick or tock return the current time, not the time of the last bar. For evaluating component specific parameters such trade statistics, call asset(Asset) and/or algo(...) at the begin of the tick function.
• The same price quote can trigger a tick function as well as a TMF. The tick functions of all assets that had quotes in the last TickTime are executed first, afterwards all triggered TMFs are executed.
• In [Test] or [Train] mode, the tick and tock functions normally run only once per bar, right before the run function at the end of the bar. When the TICKS flag is set, the tick function runs at any new price quote of any asset in the historical data, and the tock function can run multiple times per bar. When a bar period is smaller than TockTime, the tock function can run less often than once per bar.
• The series function can not be called in any of the above functions; this includes indicators that internally create data series. However, series in global variables can be evaluated, and static series or arrays can be shifted in a tick or tock function by calling shift. In this way tick based indicators or indicators on time frames shorter than BarPeriod can be used.
• As long as the current bar is not finished, the current candle is incomplete in any of the above functions. Its range and height differs to the preceding complete candles and should therefore normally not be used for indicators and trade signals. The price functions reflect the current tick and return different values than in a run function. priceC() is the current price at the time of the tick.
• Trading with different assets in the same tick function can cause backtest snooping bias. When historical price ticks for assets A and B have the same time stamps, the tick function will first run with asset A, then with asset B. In the first run, asset A has the current price, but asset B still the previous price. This can be used to snoop the next B price especially when it strongly depends on the A price. This is a rare and mostly theoretical issue, but to prevent it, you can use the tock function instead of tick for trading multiple assets. The tock function is asynchronous to price quotes. Set TockTime to the tick resolution of the used historical data, or to TickTime in live trading.
• When printing inside a error function, make sure that the printed text does not contain any of the trigger words. Otherwise you'll get an endless loop.

Examples (see also HWnd):

// print every price quote in a file
function tick()
{
  file_append("Log\\ticks.txt",
    strf("\n%i.%i %2i:%2i:%2.3f => %s %4.5f",
      day(),month(),hour(),minute(),second(),Asset,priceClose())); 
}

// shift a static series in a tick function
vars MySeries; // use a global series variable

function tick()
{
  ...
  shift(MySeries,priceClose(),100); // shift the series
  ...
}

function run()
{
  ...
  MySeries = series(0,-100); // generate a static series
  ...

See also: