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Revision as of 10:28, 18 April 2007 by Mscheffler (Talk)
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An object declared as, for example

   def foo implements pbc {
       to __optUncall() { return [1, "add", [2]] }
       # ...

will be passed-by-construction across CapTP. This means that its __optUncall() method will be called on the sending side, the elements of the result triple will be passed, and the corresponding triple as received will be called (here, as “, "add", [2])”) to create the object as received.


The first part of the example is a maker for a 2D Vector. The created vectors are Pass By Construction, they should pass the guard :pbc. The method __optUncall is a [Miranda_Method miranda method]. When the vector is copied to another [vat], the method __optUncall is called by the CapTP networking subsystem of E. The result of the method is used to recreate the object in the destination [vat]. This code should be positioned in a file in the java classpath at the location "tests.makeVector.emaker"

def makeVector implements pbc {

   to run(var x, var y) {
       def vector implements pbc {
           to getX() :any { return x }
           to getY() :any { return y }
           to __optUncall() :any { return [makeVector, "run", [x,y]] }
           to __printOn(out) {out.print(`<Vector $x $y>`)}
       return vector
   to __optUncall() :any {
       return [<import>, "get", ["tests.makeVector"]]


Example of usage:

#create a new Vector object ? def makeVector := <import:tests.makeVector&lgt;

  1. value: <makeVector>

? def vector := makeVector(6.6,7.7)

  1. value: <Vector 6.6 7.7>
  1. create a new vat

? introducer.onTheAir()

  1. value: ["3DES_SDH_M2", "3DES_SDH_M"]

? def seedVatAuthor := <elang:interp.seedVatAuthor>(<unsafe>).virtualize((introducer))

  1. value: <virtualSeedVat>
  1. source code for the new vat

? def scriptSource:="def run(thing :pbc) {println(`Thing: $thing`)}"

  1. value: "def run(thing :near) {println(`Thing: $thing`)}"

? def [scriptObj, vat] := seedVatAuthor(scriptSource)

  1. value: [<Promise>, <Vat newVirtualSeedVat in <runs in newVirtualSeedVat>>]

? scriptObj <- run(vector)

  1. value: <Remote Promise>

? Thing: <Vector 6.6 7.7>

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