[R] demo()

[Duncan Murdoch]

On 10/19/2006 6:16 PM, Yurii Aulchenko wrote:
> Dear All,
> 
> I am programming a demo for an R package (say, the name is "mydemo"); when
> I run it, it works perfectly fine.
> 
> Now is the problem: I would like some explanatory text to appear before
> the command recorded in mydemo runs. If I use "cat" or "print", the result
> is not nice: first, the comment appears as the command, and then it is
> printed out. See what I mean:

There isn't an easy way to do this.  You could write a function that 
returns an invisible result, and pass the comments to it, e.g.

m <- function(...) invisible(0)

m("This command will show a histogram of x:")

and you'll see the call but no result.  Obviously, this is kind of kludgy.

What would be nicer would be if comments in the demo() code were echoed 
to the console, but currently the comments are completely lost.

Duncan Murdoch
> 
> In mydemo code I have
> 
> # This command will show a histogram of x:
> cat("This command will show a histogram of x:\n";
> hist(x)
> 
> What appears in the output is something like:
> 
>> cat("This command will show a histogram of x:\n";
> This command will show a histogram of x:
>> hist(x)
> <<histogram is generated>>
> 
> What I would like to have as the output is:
> 
> This command will show a histogram of x:
>> hist(x)
> <<histogram is generated>>
> 
> Could someone suggest me a solution?
> 
> Yurii
> 
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