Inspect or use a Rust-like explicit trait — trait

Methods are validated by S7 on isolated tables before registration is published. Method bindings and the implementation record are published together; a publication error restores the touched bindings. Aliases for the same generic must supply identical implementation functions.

Usage

trait_methods(trait, inherited = TRUE)

impl_trait(
  trait,
  class,
  methods = list(),
  assoc_types = list(),
  assoc_consts = list(),
  replace = FALSE
)

trait_report(x, trait)

has_trait(x, trait)

assert_trait(x, trait, arg = deparse(substitute(x)))

trait_call(trait, method, x, ...)

trait_assoc_type(trait, x, name)

trait_assoc_const(trait, x, name)

Arguments

trait: A trait created by new_trait().
inherited: Include inherited methods from supertraits?
class: A concrete S7 class, S3 class wrapper, S4 class, or base class wrapper. Register union members separately. Dispatch wildcards (class_any and class_missing) are not concrete targets.
methods: Named list of method implementations. Omitted trait methods use their default implementation when one is available.
assoc_types: Named list of associated type values.
assoc_consts: Named list of associated constant values.
replace: Replace an existing implementation record and silence warnings about visible S7 methods?
x: An S7, S3, S4 or supported base-class object, or its class descriptor.
arg: Name to use in error messages.
method: Method name within the trait.
...: Additional arguments passed to the S7 generic.
name: Associated item name.

Value

trait_methods() returns a named list of trait_method() objects. impl_trait() returns the stored implementation record, invisibly. trait_report() returns a one-row data frame. has_trait() returns a single logical value. assert_trait() returns x, unchanged. trait_call() returns the result of the underlying S7 generic. trait_assoc_type() and trait_assoc_const() return the stored associated item value.