[Rd] Off-topic: Pretty-printing R (or S) code with GNU a2ps

Kurt Hornik Kurt.Hornik@ci.tuwien.ac.at
Sun, 25 Feb 2001 14:52:09 +0100


>>>>> Peter Dalgaard BSA writes:

> Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at> writes:
>> R-lang says:
>> 
>> The following identifiers have a special meaning and should not
>> be used for object names
>> 
>> if else repeat while function for in next break
>> TRUE FALSE NULL NA Inf NaN
>> ... ..1 ..2 etc.
>> 
>> so I think this is the list of keywords to use.
>> 
>> (Yes switch() is not in there ...)

> switch() is technically a function call...

> The true authority is the keywords[] array in gram.y, a study of which
> indicates that ..1, ..2 et al. do bit count as keywords, whereas ...
> does and we have an extra which was new to me, namely GLOBAL.ENV, and
> truly enough:

>> GLOBAL.ENV
> <environment: R_GlobalEnv>
>> GLOBAL.ENV <- 5
> Error in <environment> <- 5 : invalid (do_set) left-hand side to
> assignment

> Wonder what that one is good for? The only symbolic reference to
> it in the entire source is in gram.c, but I suppose its value gets
> initialized somewhere. Looks like a relic from older times, but I
> wouldn't dare to remove it for 1.2.2...

Fascinating.  Maybe file it as a bug report so that we do not forget to
fix this in the future?

-k
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