Cutout

Templating that costs nothing at runtime.

A source generator that renders Liquid style templates into a StringBuilder at compile time, so generated code keeps its indentation without a template engine dependency.

dotnet add package Cutout

Why?

A source generator has to emit source code as a string, and that string has to keep its indentation. The two usual answers each cost something:

IndentedTextWriter is fast, but the template becomes a wall of WriteLine calls
a template engine reads well, but it runs at runtime, and every generated file pays for it

Cutout renders the template at compile time. The template stays readable and the generated code is a straight line of builder.Append calls.

This template,

[Cutout.Template("{% if product == \"Awesome Shoes\" %} These shoes are awesome! {% else %} These shoes are not awesome! {% end %}")]
public static partial void Test(this StringBuilder builder, string product);

produces this method,

internal static partial void Test(this StringBuilder builder, string product)
{
    if ( product == "Awesome Shoes" )
    {
        builder.Append(@" These shoes are awesome! ");
    }
    else
    {
        builder.Append(@" These shoes are not awesome! ");
    }
}

There is no template engine at runtime; the code above is what runs.

What it does not do

It is not a runtime template engine. Rendering happens at compile time, so a template cannot be read from a file or built at runtime
Templates must be compile-time constants: a const string or a literal in the attribute
It is not full Liquid. Every block closes with {% end %}, there are no Liquid filters, and the expressions are C# expressions
Templates have to be in the compilation unit that uses them; the generator does not render templates from another project

Cutout

Why?

What it does not do

See also