Strict lists
A strict list is essentially a normal list() but it does not
allow partial matching with $.
strict_list(...) as_strict_list(x) ## S3 method for class 'xfun_strict_list' x$name ## S3 method for class 'xfun_strict_list' print(x, ...)
... |
Objects (list elements), possibly named. Ignored in the
|
x |
For For |
name |
The name (a character string) of the list element. |
To me, partial matching is often more annoying and surprising than
convenient. It can lead to bugs that are very hard to discover, and I have
been bitten by it many times. When I write x$name, I always mean
precisely name. You should use a modern code editor to autocomplete
the name if it is too long to type, instead of using partial names.
Both strict_list() and as_strict_list() return a list
with the class xfun_strict_list. Whereas as_strict_list()
attempts to coerce its argument x to a list if necessary,
strict_list() just wraps its argument ... in a list, i.e., it
will add another list level regardless if ... already is of type
list.
library(xfun) (z = strict_list(aaa = "I am aaa", b = 1:5)) z$a # NULL! z$aaa # I am aaa z$b z$c = "create a new element" z2 = unclass(z) # a normal list z2$a # partial matching z3 = as_strict_list(z2) # a strict list again z3$a # NULL again!
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.