[Rd] demo enhancement

[Duncan Murdoch]

Kjell Konis wrote:
> Hello,
>
> I have a package for working with Bayesian networks (RHugin - on R- 
> Forge for those interested). It contains a function RHExample that  
> does the same thing as the demo function in the utils package except  
> that it does not display any output in the R console. I use it to  
> build simple networks in the examples section of my .Rd documentation  
> files. Anyway, I thought it would be useful if this functionality was  
> also part of the demo function. The attached diff adds an echo  
> argument to demo which, when set to FALSE, makes demo behave the same  
> as my RHExample function. Please feel free to use it if you think it  
> would be helpful.
Your attachment got lost, but by coincidence, I was wanting an 
echo=FALSE argument to demo a couple of days ago.  I didn't add it yet, 
because

 - I'd like consistency with example(), which suggests putting echo 
ahead of verbose
 - I'd rather not add a parameter in the middle of the list, just in 
case someone has used positional args
 - example() has other args not in demo(), i.e. local, setRNG, ask, 
prompt.prefix.  Should some or all of those be added at the same time?

Since the first two items above are contradictory, I decided this needed 
thinking about, but I haven't taken the time to do that yet.

Duncan Murdoch