new2: Alternative S4 Constructor

In pkgmaker: Package development utilities

Description

An alternative version of new to create objects based on a list of values.

Usage

  new2(class, ...)

Arguments

class	Class name to instanciate
...	extra arguments from which slot values are extracted by exact matching of names.

Examples

setClass('A', contain='character', representation(x='numeric', y='character'))

# identical behaviour with standard calls
identical(new('A'), new2('A'))
identical(new('A', x=1), new2('A', x=1))

# but if passing that are names not slots
identical(new('A'), new2('A', b=1))
identical(new('A', x=1), new2('A', x=1, b=3))
identical(new('A', x=1), new2('A', x=1, b=3))

# standard `new` would coerce first unnamed argument into parent of 'A' (i.e. 'character')
new('A', list(x=1))
new('A', list(x=1, y='other'))
# `new2` rather use it to initialise the slots it can find in the list
identical(new('A', x=1), new2('A', list(x=1)))
identical(new('A', x=1, y='other'), new2('A', list(x=1, y='other')))

pkgmaker documentation built on May 2, 2019, 4:42 p.m.