This functions checks the evaluation of an expression and, if an error is thrown, captures it and integrates the captured message after a custom error message.
check_expr(expr, ..., clean, up = 0, arg_name, verbatim = FALSE)
check_expr_hook(expr, ..., clean, arg_name, verbatim = FALSE)
generate_check_expr_hook(namespace)An expression to be evaluated.
Character scalars. The values of ... will be coerced with the function
string_magic.
This means that string interpolation is allowed. Ex: "Arg. {arg} should be positive"
leads to "Arg. power should be positive" if arg is equal to "power".
If argument verbatim is TRUE, the values are instead coereced with paste0.
Character vector, default is missing. If provided, the function
string_clean
is applied to the captured error message to clean it when necessary. Each element
of the vector should be of the form "pat => rep" with pat a regular expression
to be replace and rep the replacement.
Integer, default is 0. It is used to construct the call in the error message.
By default the call reported is the function containing check_expr. If you want to
report a function higher in the stack, use up = 1, or higher.
Character scalar, default is missing. Used when the expression in
expr leads to an error and the custom message is missing (i.e. no element is
provided in ...). In that case, the default message is: "The argument {arg_name} could not be evaluated.".
The default value for arg_name is deparse(substitute(expr)), if this guess is wrong,
use arg_name.
Logical scalar, default is FALSE. By default the elements of ...
allow string interpolation with "{}" using stringmagic.
If TRUE, no interpolation is performed.
Character scalar giving the namespace for which the hooks are valid. Only useful when hook functions are used in a package.
The purpose of this functions is to provide useful error messages to the user.
check_expr_hook(): As check_expr but sets the error call at the level of the hooked function
generate_check_expr_hook(): Generates a package specific check_expr_hook function
For general argument checking, see check_arg() and check_set_arg().
test = function(x, y){
check_expr(mean(x, y), "Computing the mean didn't work:")
}