constant-generator

A .Net Source Generator that converts XML to C# compile time constants.

Introduction

Sometimes you need structured constants, for example various paths or routes but manually creating those constants is error prone, a chore, or both. With this code analyser type library you can describe them as XML with minimal repetition and almost no bolerplate. You can nest fragments in a way that's easy to comprehend at a glance and the analyser automatically creates the nested static classes and string constants with the full paths glued together as values.

Usage

Include this project using ProjectReference with the attributes you see below. Also Include your files into the AdditionalFiles item group:

    <ItemGroup>
        <ProjectReference Include="..\ConstantGenerator\ConstantGenerator.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
        <AdditionalFiles Include="*.constants.xml" />
    </ItemGroup>

Example

Say you want custom routes for your ASP.Net application, but also put it in a constants file so you can refer to them in your logic.

sample.routes.constants.xml

<?xml version="1.0" encoding="utf-8" ?>
<Management xmlns:g="https://github.com/DAud-IcI/constant-generator/">
    <!-- Without this, your class will be in the Constants namespace. That can work if the file names are unique. -->
    <g:Namespace Value="ConstantGenerator.Sample.Constants.Routes" />
    
    <!-- This is the default already so you can safely omit it. -->
    <g:Separator Value="/" />

    <Users />
    <Companies />
    <New>
        <User />
        <Company />
    </New>
    <Unassign>
        <User />
    </Unassign>
</Management>

The elements with the g namespace are optional configuration items, they are optional, must be direct children of the root and each must have a Value attribute.

Namespace: You can specifiy the generated class's namespace. If you omit it, it will use Constants.
Separator: The values in the constants are the full path from the root, with this string used as the separator. The default value is /.

It generates this class:

SampleRoutes.GeneratedConstant.cs

namespace ConstantGenerator.Sample.Constants.Routes
{
    public static class Management
    {
        public const string ThisRoute = "Management";

        public const string Users = "Management/Users";
        public const string Companies = "Management/Companies";

        public static class New
        {
            public const string ThisRoute = "Management/New";

            public const string User = "Management/New/User";
            public const string Company = "Management/New/Company";
        }

        public static class Unassign
        {
            public const string ThisRoute = "Management/Unassign";

            public const string User = "Management/Unassign/User";
        }
    }
}

This seems pretty simple, so why?

For one it saves a lot of lines and boilerplate on more complex structures. Also if you did this manually you probably should have auxiliary variables like this:

        public static class New
        {
            private const string NewPathBase = nameof(Management) + "/" + nameof(New);
            public const string User = NewPathBase + "/" + nameof(User);
            public const string Company = NewPathBase + "/" + nameof(Company);
        }

Don't get me wrong, nameof is great but just look at all this visual noise! We don't need that with the source generator beucase the name is generated from the same text as the value.

Future Plans & Contributing

This project is my attempt to learn .Net source generators while making something I can actually see myself using. I plan to get out a NuGet release after the code is cleaned up, but outside of that I don't see much in way of future improvement. Of course if you have any suggestions, pull requests are welcome.

sarahelsaig / constant-generator Goto Github PK