From ruipb@rr@d@@ @ending from @@po@pt  Sat Oct  6 19:42:52 2018
From: ruipb@rr@d@@ @ending from @@po@pt (Rui Barradas)
Date: Sat, 6 Oct 2018 18:42:52 +0100
Subject: [Rd] Warning when calling formals() for `[`.
In-Reply-To: <CA+JCgN254QaHVepo03ZuGLsatwmjfDSnUP3yq43N6TguBdWN5g@mail.gmail.com>
References: <CA+JCgN254QaHVepo03ZuGLsatwmjfDSnUP3yq43N6TguBdWN5g@mail.gmail.com>
Message-ID: <f5d15068-0776-2b5e-11d7-b1ae6ffc1d3b@sapo.pt>

Hello,

I believe that this is maybe not a *feature* but at least expected 
behaviour.

The call formals(args(`[`)) breaks down to


 > args(`[`)
NULL
 > formals(NULL)
NULL
Warning message:
In formals(fun) : argument is not a function


Hope this helps,

Rui Barradas


?s 18:26 de 06/10/2018, Laurent Gautier escreveu:
> Hi,
> 
> A short code example showing the warning might the only thing needed here:
> 
> ```
>> formals(args(`[`))
> NULL
> 
> *Warning message:In formals(fun) : argument is not a function*
>> is.function(`[`)
> [1] TRUE
>> is.primitive(`[`)
> [1] TRUE
> ```
> 
> Now with an other primitive:
> 
> ```
>> formals(args(`sum`))
> $...
> 
> 
> $na.rm
> [1] FALSE
> 
>> is.function(`sum`)
> [1] TRUE
>> is.primitive(`sum`)
> [1] TRUE
>> class(`[`)
> [1] "function"
> ```
> 
> Is this a feature ?
> 
> 
> Laurent
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
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>



[Rd] Warning when calling formals() for `[`.
Rui Barradas