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This function is used by Ignition's Expression language.

Description

Runs a single line of Python code as an expression. If a poll rate is specified, the function will be run repeatedly at the poll rate. This is a very powerful way for you to add extensions to the expression language. For example, one could write a project script module function called shared.weather.getTempAt(zip) that queried a web service for the current temperature at a given zipcode, and then bind the value of a label to the return value of that function.

The scriptFunction is a entered as a string and the pollRate is in milliseconds. You can optionally add any function arguments after the poll rate.

runScript Polling in Tags

The runScript function can be used in expression tags, but the poll rate doesn't work exactly the same as in an expression binding. All Tags have a Scan Class that dictates the minimum amount of time between each evaluation. The runScript poll rate only polls up to the rate of the scan class set on the tag.

For example, if an Expression Tag is configured with runScript to run at a poll rate of 60 seconds and is using the "default" (1 second) scan class, the Tag's Expression will still execute every 1 second. So a scan class rate of 60 seconds will be necessary for a runScript expression to poll at any rate between 0 and 60 seconds.

Syntax

 runScript(scriptFunction[, pollRate][, args...])

  • Parameters

string scriptFunction - A single line of python code. Typically the path to a script module.

int pollRate - Optional. The poll rate of the script.

object args - Optional. Any number of argument objects that will be passed into the given script.

  • Results

object - The return value of the specified function.

Examples

Here is our scripting function we are going to run that is located in a shared script called textScript.

Code Snippet - Python Function
def myFunc(text="Hello World!"):
	return text
Code Snippet
// run a shared function with this expression
runScript("shared.textScript.myFunc()", 0) //This would run the script and return "Hello World!".
Code Snippet
// run a shared function dynamically with this expression
// using string concatenation. A poll rate is unnecessary, as it will refresh when the tag value changes.
runScript("shared.textScript.myFunc('" +{_gensim_/Writeable/WriteableString1} + "')", 0) // This would run the function and pass in the value of the WriteableString1 tag.
Code Snippet
// run a shared function dynamically with this expression
// using optional arguments. A poll rate is unnecessary, as it will refresh when the tag value changes.
// Note the missing "()" at the end of the scriptFunction string
runScript("shared.textScript.myFunc", 0, {_gensim_/Writeable/WriteableString1})
  • No labels

4 Comments

  1. Anonymous

    Can an example be provided for runScript with arguments?

    1. Anonymous

      Here is an example, where the root container has a custom function called "calculateAggregates(dataset)":

      runScript("self.calculateAggregates", 0, {Root Container.MyDataSet})

  2. Anonymous

    What are the units of poll rate?  msecs?

    1. Robert McKenzie

      Yes!