[R] backticks

[Peter Dalgaard]

Robin Hankin wrote:
> I noticed just now that
> package.skeleton() produces R files in which
> the function names are escaped with backticks.
>
> ?Quotes says that "The preferred quote is the backtick (`)",
> but I don't understand _why_  this is preferred.
>
> ?formula gives some clues but points out that there
> are no guarantees that formulae using non-syntactic names such as
> `like this` will be accepted.
>
> What exactly do backticks do that single or double quotes don't?
>   
I don't know whether we really want to be that dogmatic about it, but in
a nutshell

`like this` <- 2
"like that" <- 3
print(`like this`)
print("like that")

I.e. backtick'ed names work whereever ordinary names do, but quoted
names work only on the LHS of assignments.

The note in ?formula should probably be understood defensively: We
intend backtick'ed names to work in all contexts, but  there may be
programming practices where the backticks are not preserved (notably if
there is a deparse-reparse step involved).

> Where do I look for documentation on this?
>
>
>
>
> --
> Robin Hankin
> Uncertainty Analyst
> National Oceanography Centre, Southampton
> European Way, Southampton SO14 3ZH, UK
>   tel  023-8059-7743
>
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>   


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