`base' package. That's why you can override them by redefining T/F in
the global environment (or somewhere farther up the search list than `base').
attach() is different because it places variables on the search list *after* the global environment.
-roger
RenE J.V. Bertin wrote:
On Thu, 07 Oct 2004 13:17:02 -0400, "Roger D. Peng" <[EMAIL PROTECTED]> wrote regarding "Re: [R] 'with' usage question"
8-) I think what's happening is that the function aov.SS1 will look up 8-) variables in the environment in which it was *defined*, which in your 8-) case (I'm guessing) is the global environment/workspace. Therefore, 8-) if `speed' and `Subject' are not defined in the global environment, 8-) they will not be found.
If you take that to the letter, doesn't it mean that attach() and detach() couldn't have the effect they have? Which is, in fact and if memory serves me well, much like the Pascal 'with' operator. A (possible) counter argument: aov.SS1() used T and F as the usual abbreviations for TRUE and FALSE: these are defined in the global environment. Now my dataframes also contain a variable T: it took me quite a while to realise that this variable (which I in fact never use directly) would override the T constant/operator and cause hard-to-trace error messages.
I'm trying to find some analogy. with() extends the current environment with the variables in the given dataframe, but does not create a C-like scope. Rather, it functions more or less like a Bourne shell script: the new variables are not 'exported' to be available to code evoked from within that new environment, unless they were specifically passed as arguments. Which still doesn't explain why ls() sees everything when called within a with() statement...
Anyway, I'd better get back to work before my gray matter shortcircuits :)
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