You may think of with Roslyn analyzers, Roslyn code generators, or open-source IL tools.
But Metalama plays in a different league.
Metalama is integrated. No other tool than Metalama allows you to both generate code that is visible at design time, and override hand-written code. You would need to use a combination of open-source tools, which do not integrate with each other, in order to achieve can Metalama can do.
Metalama is much simpler. Doing meta-programming well at at the abstraction of Roslyn or MSIL is very complex (think years of experience needed, not months). Done naively, low-level metaprogramming is comparable to hacking. It can significantly increase complexity, especially after the developer who implemented the meta-code leaves the team.
Metalama is engineered for good architecture. Metalama is designed to simplify development. It does not offer hacks that make the code less predictable or understandable. There are three cultures in software development: hacking, science, and engineering. We belong to the last one, while staying attentive to both other.
Metalama is a complete, well-though-out solutions. Alternatives focus on the most frequent use cases and cut corners – for instance they don’t not properly implement async methods. PostSharp goes the extra mile and adds enough extension points so that you never get stuck.