I think the point @ahundiak is trying to make is that it is so obvious that this variable refers to your database connection that you should substitute that name instead, and that if you need that to be explained, then something is wrong after all these posts.
Example please, of a prepared statement in PDO that does not use placeholders?
I don't think I'd agree with that interpretation. The idea of a wrapper is not that you paste your code into an exe and that "converts" your code and then spits out the completed version. That's more of a type of code-completion, or like the code snippets in Visual Studio. To me, a wrapper is a function or a series of functions that you keep in a library and call when you need them, and those functions (like any function, really) do the repetitive things that you don't want to keep typing out.