csvReader: how to read only selected columns while the class Layout has extra field?

[mw]

On Sunday, 2 October 2022 at 21:03:40 UTC, rassoc wrote:

> But say, I'm curious, what's the purpose of adding an 
> optional/useless contents field? What's the use-case here?


We have a class/struct for a data record,
some of its data fields need to be saved/loaded from CSV files; 
while there are other helper fields which are useful for various 
computation tasks (e.g. caching some intermediate computation 
results), these fields do not need to be saved/loaded from the 
csv files.


A CSV library should consider all the use cases, and allow users 
to ignore certain fields.