Use consistent input checking about kirkegaard HOT 4 OPEN

Other options.

https://cran.r-project.org/web/packages/ensurer/vignettes/ensurer.html

from kirkegaard.

Actually I quite like the is_ function. Flexible. Can be made more flexible by adding the half equation, math function support. Maybe use a formula e.g. ~<2 is shorthand for x<2, where x is the variable.

from kirkegaard.

I deleted check_missing. Pointless function. All one has to do is call each of the arguments. If it's actually missing, R displays the standard missing argument error to the user.

from kirkegaard.

Neither package turned out to be useful for my purposes. assertthat has no easy way to make custom error messages, it has to be done in some complicated functional way. ensurer has the same problem, except it's worse.

So I rolled my own simple function: fail_if. It simply evaluates the input and throws an error with a custom message message if it is true.

from kirkegaard.