> The specification must include a written description of the invention and of the manner and process of making and using it, and is required to be in such full, clear, concise, and exact terms as to enable any person skilled in the technological area to which the invention pertains, or with which it is most nearly connected, to make and use the same.
You don't have to provide code, but you have to teach the reader of your patent how to make and use the invention.
It does? Exactly zero of the companies I've worked for in my career have forbidden me from reading patents.
Given how many patents are vaguely worded, and how, um, interesting the decisions in patent cases sometimes come out, many companies decide that it isn't worth the risk.
Note well: IANAL. I've just been in companies that had this practice (don't read patents), and I remember why.