Parameters

Parameters are the settings of a script. The terminal builds the settings dialog from them, and every run applies the values the user chose.

QuaScriptengine result

Loading the engine result…

params.qs

analysis "Parameters" { overlay = true }

len    = param.int(20, title = "Length", min = 1, max = 500, group = "Average")
mult   = param.float(2.0, title = "Width", min = 0.1, step = 0.1, group = "Average")
src    = param.source(close, title = "Source")
kind   = param.choice("ema", title = "Average", options = ["ema", "sma", "hull"])
show   = param.bool(true, title = "Show band")
tone   = param.color(color.sky.400, title = "Color")

// a match on a parameter runs only the selected branch, on every bar
avg = match kind {
    case "ema" { ta.ema(src, len) }
    case "sma" { ta.sma(src, len) }
    else { ta.hull(src, len) }
}
dev = stat.stdev(src, len) * mult
render.line(avg, "Average", color = tone)
pu = render.line(show ? avg + dev : na, "Upper", color = tone, width = 1)
pd = render.line(show ? avg - dev : na, "Lower", color = tone, width = 1)
render.band(pu, pd, color = color.sky.500, opacity = 0.08)

quatick-charts · QuaScript engine on synthetic 1-minute bars · drag to pan · scroll to zoom · Run executes the script on the engine (⌘/Ctrl+Enter while editing)

Kinds

Function	Value	Notes
`param.int`	integer	`min`, `max`, `step`
`param.float`	number	`min`, `max`, `step`
`param.bool`	bool	a checkbox
`param.choice`	text or enum member	`options = [...]`, or an enum member as the default
`param.text`	text
`param.color`	color
`param.source`	series	`open high low close volume bar.mid bar.typical bar.average bar.weighted`
`param.interval`	interval text	`"15"`, `"60"`, `"4h"`, `"1D"`; for feeds
`param.symbol`	symbol text	for feeds of another instrument
`param.time`	epoch seconds

Common arguments: title, id, group (a section in the dialog), row (parameters with the same row share a line), tooltip.

Ids

Every parameter has an id used to set it from outside: id if given, otherwise the title in snakecase (`"Fast length"` → `fastlength), otherwise the variable name. Two parameters with the same id are an error (EPARAMDUP`).

terminal.sh

quas run params.qs data.csv --set length=50 --set average=hull --set show_band=false

Values are checked against the kind and limits; an unknown id or an out-of-range value is rejected with a message naming the parameter.

Defaults are constants

The default must be a literal (or an enum member), so the settings dialog can show it before the script runs. A parameter's value is the same on every bar, so match on a parameter computes only the selected branch and does not trigger the conditional-state warning.

Appearance

Parameters

Kinds

Ids

Defaults are constants