[Rcpp-devel] Checking for a promise

[Gabor Grothendieck]

How do I fix this so it works?  The code is intended to return TRUE or
FALSE according to whether the variable with name nm in environment
env is a promise or not.  In the example code below it returns FALSE
but I would like it to return TRUE.  Is the promise being forced
somewhere along the way?  Some other problem?

library(Rcpp)
f <- cxxfunction(signature(env="environment", nm = "character"),
        body=' Environment e(env);
           std::string s = as<std::string>(nm);
           return wrap(TYPEOF (e[s]) == PROMSXP); ',
        plugin="Rcpp")

# create promise
delayedAssign("prom", 3)

# want it to return TRUE but it returns FALSE
f(.GlobalEnv, "prom")


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