Wrapping JME code in an extension?

[Ulrich Goertz]

Hello, I was wondering whether it is possible to put code for a JME function into an extension and "evaluate" it there so that the extension can expose a callable which applies the JME function.

(I have a collection of JME functions for my linear algebra problems, such as creating a random matrix in row echelon form, applying some random elementary row transformations, etc. In principle they could be rewritten in Javascript, but the JME code is usually quite short and has the advantage that it is easier to plug in different base fields.)

I have seen that an extension can define/expose functions that are then callable from JME, but in all the examples I have seen, the function body was just Javascript. I am missing the piece that would parse the JME code, plug in the arguments and retrieve the result. It seems that something like that has to happen when an exam is imported as a JSON file and the JME functions defined there are turned into callables.

Thanks for any pointers!

Best, Ulrich

[Christian Lawson-Perfect]

The code that is used to make up custom functions defined in questions is in Numbas.jme.variables. There's a function Numbas.jme.variables.makeFunction which does what you want. Here's an example extension, adding a function 'versin' defined as 1-cos(x):

Numbas.addExtension('wrap-jme-function',['jme'],function(extension) {
  var scope = extension.scope;

  scope.addFunction(Numbas.jme.variables.makeFunction({
    language: 'jme',
    name: 'versin',
    definition: '1-cos(x)',
    parameters: [
      {name: 'x', type: 'number'}
    ]
  },scope));
});

I hope that helps!

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[Ulrich Goertz]

That's exactly what I was looking for, thanks! Ulrich