Function that supplies value, can also encapsulate alot of data generation code. After that you can write a strategy to select which data generation algorithm (supplier) shpuld be used.
Just maybe he genuinely doesn't know what you mean. I mainly use Python and have no idea what you are talking about.
(You might consider reflecting on your tone and message. It presupposes bad faith on the other party, is dismissive and condescending, and you are probably less right than you think you are.)
In case of more complex data generation you could use supplier pattern and combine it with strategy.
No need for any if else statements at all.
Sure it requires a lot more of work but is future proof and clear.