[R] The Suggests field in a DESCRIPTION file --- never mind!!!

[Rolf Turner]

I figured it out.  The package name in the call to requireNamespace() 
has to be a *text string*.  I should've had:

     fortOK <- requireNamespace("fortunes",quietly=TRUE)

So require() takes a package name, but requireNamespace() takes a 
*string* specifying the package name.  Trap for young players.

Psigh.

cheers,

Rolf Turner

On 11/18/18 11:16 AM, Rolf Turner wrote:
> 
> I am building a package which contains a function from which I wish to 
> call the fortune() function from the fortunes package --- if that 
> package is available.
> 
> I have place the line
> 
>     Suggests: fortunes
> 
> in the DESCRIPTION file.
> 
> In my code for the function that I am writing (let's call it "foo")
> I put
> 
>> fortOK <- requireNamespace(fortunes,quietly=TRUE)
>>         if(fortOK) {
>>             fortunes::fortune()
>>         }
> 
> thinking that I was following all of the prescriptions in "Writing R 
> Extensions".  Yet when I do R CMD check on the package I get
> 
>> * checking R code for possible problems ... NOTE
>> foo: no visible binding for global variable ‘fortunes’
>> Undefined global functions or variables:
>>   fortunes
> 
> What am I doing wrong?
> 
> Thanks for any insight.
> 
> cheers,
> 
> Rolf Turner
> 
> P. S.  I tried putting an "imports(fortunes)" in the NAMESPACE file, but 
> this just made matters worse:
> 
>> * checking package dependencies ... ERROR
>> Namespace dependency not required: ‘fortunes’
> 
> Huh?  What on earth is this actually saying?  I cannot parse this error 
> message.
> 
> R. T.
> 


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