I'm writing a package for reading text files in an industry-standard format. Because the format (which is fixed-width) reserves space for custom fields, the package needs to allow users to define those fields. I decided to define a class named
record_format for users to organize that data. Right now, the class is just a
data.table with certain columns.
I'd like my package to eat its own dogfood and store the official field definitions as a
record_format object. But this risks a loop when building the package: the data is created using a function in the package, which cannot be built until the data is created.
R's official documentation says data files can be
.R scripts, but it then says
Note that R code should be “self-sufficient” and not make use of extra functionality provided by the package
So what's a good way to do this?