predicates: Basic predicates for validation

In egnha/rong: Functional Input Validation

Description

The following predicate functions augment predicates from the base and rlang packages to enable them to produce informative error messages when used as checks in fasten(), firmly(), validator(), validate().

• Boolean predicates

• Object predicates

• Pattern predicates

• Property predicates

• Relational predicates

• Set predicates

• Type predicates

Examples

## chk_double() and rlang::is_double() are identical as functions
chk_double(runif(2))
chk_double(runif(2), n = 1)
chk_double(1:2)
rlang::is_double(runif(2))
rlang::is_double(runif(2), n = 1)
rlang::is_double(1:2)

## But when rlang::is_double() is used in firmly(),
## it produces an auto-generated error message ...
## Not run: 
firmly(function(x) x, rlang::is_double(n = 1))(runif(2))
## End(Not run)

## ... whereas chk_double() produces a specialized error message
## Not run: 
firmly(function(x) x, chk_double(n = 1))(runif(2))
## End(Not run)

## Not run: 
validate(mtcars, is.matrix, {"cylinder" %in% names(.)})
validate(mtcars, chk_matrix, chk_has_name("cylinder"))
## End(Not run)

egnha/rong documentation built on May 7, 2019, 9:48 p.m.