Using `:=` from data.table when data.table package is not loaded?

Question

I want to use := operator from data.table without loading data.table. For example for the following data.table, I want to add another column called error:

DT <- data.table::data.table(station = rep(1:1,52560), mod = rnorm(1*52560),obs = rnorm(1*52560))

If I do the following everything goes well, however, I am puzzled how it worked without referring to package data.table (the data.table library is not loaded)?!!

DT[ , `:=`(error  = mod - obs)]

How can I rewrite the above line using data.table::::= ?!!

Answer 1

Not sure I understand correctly, but regarding :

I am going to use this in another package and preferably I want not to load data.table. – newbie

I am importing the package, I have no other choice since data.table will not work if I do not import. Would importing alone take care of this? – newbie

Yes Import data.table rather than Depend on it from your package. You may have tried that and it didn't work because of this common issue. See solution here :

Using data.table package inside my own package