CalcManager Packaging

[tian-lt]

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

Package Name	Description
Ratpack	Rational Package - to do arbitrary-precision rational math calculation
CalcEngine	Abstraction of the calculation and commands used in Calculator
CalcManager	Integration of different CalcEngine modes (Standard, Scientific, ...)

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

	C API	COM	WinRT
Supported Platforms	All	Windows Only	Windows Only
Supported Languages	All thru FFI	All with great efforts	C/C++/C#/Rust/Python with WinRT library All with great efforts
Programming Paradigm	Procedure-oriented	OOP	OOP
Development Experience	Easy😊	Painful😱	Medium😐
Community Engagement	Widely used	😒	Not popular yet
Error Handling	Catch all explicitly and return error code	Catch all explicitly and return HRESULT	Catch all implicitly by C++/WinRT library and return HRESULT

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