The typical process of checking arguments in functions is iterative. In this process, an error may be returned and the user may fix it only to receive another error on a different argument. 'ArgumentCheck 'facilitates a more helpful way to perform argument checks allowing the programmer to run all of the checks and then return all of the errors and warnings in a single message.
Checking function arguments can be done in a manner that allows all of the problems in the arguments to be noted and returned to the user in a single call. This avoids the potentially iterative process of finding problems in one argument, fixing the error, and going on to find problems in subsequent checks. The ArgCheck object can store messages for all of the problems and return these messages all at once, allowing the user the opportunity to fix all of the arguments before proceeding.
match_arg matches arg against a table of candidate values as specified by choices, where NULL means to take the first one. This is a modified version of the base package function match.arg that differs only in that it can interact with ArgumentCheck environments.
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