CalcManager Packaging

Problem Statement

Currently, CalcManager/CalcEngine is implemented in C++ as part of Calculator. Some teams may want to reuse it as an independent library package. Besides, if we want to convert Calculator App to C#, we need to wrap the CalcEngine in C#.

Evidence or User Insights

Potential Consumers

• PowerToys (currently use https://github.com/FlorianRappl/Mages , and they want to switch off it)

Proposal

Concepts

Functional Requirements

• Calculator Engine
  (accept operator/operand commands and calculate the result to display)
• Arbitrary-precision rational calculation
• Expression parsing *
  • Localization support *
  • Customizable aliasing (e.g. arcsin v.s. inverse sin v.s. sin^-1) *
• Expression evaluation *

The requirements with star (*) are not implemented yet, but will be published eventually.

Usage Requirements

CalcEngine will be consumed by ourselves and 1P teams thru NuGet package.

For us, we need a C# wrapper for CalcEngine, because we will do C# conversion for Calculator App.

In sum, we have the following usage requirements:

• Independent NuGet package
• C# wrapper

Portability Requirements

OS

• Windows
  • x86
  • x64
  • ARM32
  • ARM64

Languages

• C/C++
• C#
  • .NET Core 3
  • .NET 5

Implementation Requirements

Ratpak and CalcEngine are implemented in C++, which won't be changed.

• Maintain Ratpack and CalcEngine in C++
• CalcEngine should remain in the Calculator repo

Design Proposal

Choice of Packaging Techniques

To enable interop between C++ and C#, we have 3 choices:

1. Expose C API from C++
   consumed by C# thru P-Invoke
2. Expose COM components from C++
   consumed by C# thru COM
3. Expose WinRT components from C++ thru C++/WinRT
   consumed by C# thru C#/WinRT

Comparison