External Function Calls

[dschwartznyc]

Problem Description:

The Rosetta runtime allows functions to be marked with [codeImplementation], indicating logic provided by the host language. The Python generator does not yet emit the syntax to delegate these calls to Python external implementations.

Steps to Reproduce:

Example Rune code: import-overlap.rosetta

func MyFunc:
  [codeImplementation]
  output:
    result int (1..1)

1. Define a Rosetta function with the [codeImplementation] annotation.
2. Attempt to generate Python code for this function.

Expected Result:

The generator should emit a call to a standard Python registry or dispatcher where the user can provide the implementation.

Actual Result:

The generator produces an empty body or fails to map the implementation.

Additional Context:

Critical for CDM validation functions like ValidateFpMLCodingSchemeDomain.

[plamen-neykov]

This sample rune:

namespace rosetta_dsl.test.functions

enum RoundingModeEnum:
    Down
    Up 

func RoundToNearest: <"Round a number to the supplied nearest, using the supplied rounding mode.">
    [codeImplementation]
    inputs:
        value number (1..1) <"The original (unrounded) number.">
        nearest number (1..1) <"The nearest number to round to.">
        roundingMode RoundingModeEnum (1..1) <"The method of rounding (up to nearest/down to nearest).">
    output:
        roundedValue number (1..1)
    condition PositiveNearest:
        nearest > 0

Should translate to this in the bundle:

@replaceable
@validate_call
def rosetta_dsl_test_functions_functions_RoundToNearest(value: Decimal, nearest: Decimal, roundingMode: rosetta_dsl.test.functions.RoundingModeEnum.RoundingModeEnum) -> Decimal:
    """
    Round a number to the supplied nearest, using the supplied rounding mode.

    Parameters
    ----------
    value : Decimal
    The original (unrounded) number.

    nearest : Decimal
    The nearest number to round to.

    roundingMode : rosetta_dsl.test.functions.RoundingModeEnum.RoundingModeEnum
    The method of rounding (up to nearest/down to nearest).

    Returns
    -------
    roundedValue : Decimal

    """
    _pre_registry = {}
    self = inspect.currentframe()

    # conditions

    @rune_local_condition(_pre_registry)
    def condition_0_PositiveNearest():
        item = self
        return rune_all_elements(rune_resolve_attr(self, "nearest"), ">", 0)
    # Execute all registered conditions
    rune_execute_local_conditions(_pre_registry, 'Pre-condition')

    roundedValue = rune_execute_native('rosetta_dsl.test.functions.RoundToNearest', value, nearest, roundingMode)


    return roundedValue

---

NOTE: the runtime already has the support for this, and there are tests showing how the external functions should be initialised for the runtime to discover them.