Rule for accessing attributes?

lst at names

-----Original Message-----
From: r-help-bounces at r-project.org 
[mailto:r-help-bounces at r-project.org] On Behalf Of Tribo Laboy
Sent: Thursday, March 27, 2008 12:16 AM
To: r-help at r-project.org
Subject: [R] Rule for accessing attributes?

Hi !

I am a new user and quite confused by R-indexing.

Make a list and get the attributes
lst <- list(x = 1:3, y = 4:6, z = 7:9)
attributes(lst)

This returns:

$names
[1] "x" "y" "z"

I can easily do:

nm <-names(lst)

or

nm <-attr(lst,"names")

which both return the assigned names of the named list 'lst', 
but why then this doesn't work:

lst$names

?

I am confused ... Moreover, I noticed that some of the objects (e.g.
plot objects returned by ggplot) also have attributes when 
queried by the 'attributes' function, but they are accessible 
by the $ notation.
(e.g.

xydf <- data.frame(x = 1:5, y = 11:15)
plt <- ggplot(data = xydf, aes(x = x,y = y)) + geom_point()
attributes(plt)

Now we can change the title:

plt$title <- "My Title"
plt

So is it some inconsistency or am I missing something important?