uCalc API Version: 2.1.3-preview.2 Released: 6/17/2026

Warning

uCalc API Preview Release Notice:The documentation describes the intended behavior of the API. The current preview build contains incomplete features, unoptimized performance, and is subject to breaking changes.

FunctionAddress = [OpCallback]

Property

Product: 

Fast Math Parser

Class: 

Item

Gets or sets the memory address of a native callback function associated with a uCalc symbol, enabling implementation sharing and runtime hot-swapping.

Remarks

🔗 FunctionAddress Property

The FunctionAddress property gets or sets the memory address of the native callback function associated with a uCalc Item. This provides a powerful link between a symbol defined in the uCalc engine (like a function or operator) and a function in the host application's native code (C#, C++, VB).

It is a key feature for advanced scenarios involving dynamic behavior, performance optimization, and code reuse.

📖 Getter: Reusing Implementations

When used as a getter, FunctionAddress retrieves the address of the native callback implementing a function's logic.

var floorAddr = uc.ItemOf("Floor").FunctionAddress;

The most common use case is to create a new function or operator that reuses the logic of an existing native-bound function. This allows you to define a new symbol with a different name or properties while pointing it to the same high-performance native code.

FunctionAddress vs. CreateAlias

It is crucial to understand the difference between sharing a function address and creating an alias with CreateAlias.

  • CreateAlias("New", "Old"): Creates a new name that points to the exact same Item. It is a simple synonym.
  • Using FunctionAddress: You can have a completely new and independent Item that just happens to point to the same native callback address. This new item can have its own distinct properties.

✍️ Setter: Hot-Swapping Implementations

When used as a setter, FunctionAddress provides a powerful mechanism to hot-swap the native code implementation of an Item at runtime.

uc.ItemOf("MyRound").FunctionAddress = ceilAddr;

This decouples a symbol's name from its concrete implementation, enabling advanced dynamic behaviors:

  • Dynamic Aliasing: Redirect one function to another. The practical example demonstrates making a custom MyRound function point first to Floor and then to Ceil.
  • Mode Switching: Switch between different implementations of a function based on context (e.g., a fast, unsafe calculation in performance mode vs. a slower, bounds-checked version in debug mode).
  • Runtime Plugin Systems: Load functions from external libraries (DLLs/shared objects) at runtime and bind them to existing function names within the uCalc engine.

💡 Why uCalc? (Comparative Analysis)

uCalc abstracts the platform-specific details of function pointers (C++) and delegates (C#) into a consistent API. This property allows you to manipulate these bindings programmatically at runtime, a task that is typically static and compile-time-dependent in native languages. While delegates and function pointers can be reassigned, uCalc provides a high-level, symbolic way to manage these bindings. You can retrieve an Item by its string name using ItemOf and then change its implementation, a level of dynamism not typically available for compiled functions.

Examples

Defining another function using the same callback address of existing one
				
					using uCalcSoftware;

var uc = new uCalc();
uc.DefineFunction("MyRound(x)", uc.ItemOf("Floor").FunctionAddress);
Console.WriteLine(uc.Eval("MyRound(2.5)"));

uc.ItemOf("MyRound").SetFunctionAddress(uc.ItemOf("Ceil").FunctionAddress);
Console.WriteLine(uc.Eval("MyRound(2.5)"));
				
			
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   uc.DefineFunction("MyRound(x)", uc.ItemOf("Floor").FunctionAddress());
   cout << uc.Eval("MyRound(2.5)") << endl;

   uc.ItemOf("MyRound").SetFunctionAddress(uc.ItemOf("Ceil").FunctionAddress());
   cout << uc.Eval("MyRound(2.5)") << endl;
}
				
			
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					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      uc.DefineFunction("MyRound(x)", uc.ItemOf("Floor").FunctionAddress)
      Console.WriteLine(uc.Eval("MyRound(2.5)"))
      
      uc.ItemOf("MyRound").SetFunctionAddress(uc.ItemOf("Ceil").FunctionAddress)
      Console.WriteLine(uc.Eval("MyRound(2.5)"))
   End Sub
End Module
				
			
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