add new entry on Date + Datetime being not exactly optimal but set

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,11 @@
+2022-04-03  Dirk Eddelbuettel  <[email protected]>
+
+	* vignettes/rmd/Rcpp-FAQ.Rmd: Add paragraph about Date(time) not
+	being aimed at parsing large quantities at once
+
+	* vignettes/rmd/Rcpp.bib: Add four entries
+        * inst/bib/Rcpp.bib: Idem
+
 2022-03-14  Dirk Eddelbuettel  <[email protected]>
 
 	* DESCRIPTION (Version, Date): Roll minor version

vignettes/rmd/Rcpp-FAQ.Rmd

@@ -1805,3 +1805,17 @@ For emphasis, here is a quote from the [rcpp-devel post](https://lists.r-forge.r
 Many code examples and packages show exactly that approach (as _e.g._ discussed
 in the [Rcpp Gallery post](https://gallery.rcpp.org/articles/plyr-c-to-rcpp/)).
 Anybody who claims otherwise is (possibly intentionally) misleading.
+
+## Converting a large number of Date objects seems slow
+
+The `Date` and `Datetime` classes, and their vector variants, go back a very
+long time to the very beginning of \pkg{Rcpp} and use in \pkg{RQuantLib}
+\citep{CRAN:RQuantLib} interfacing \pkg{QuantLib} \citep{QuantLib}. Their intent was,
+essentially, to hold (single) start and end values delineating an interval.  The
+design is far from optional, but the interface is now established. We have
+rewritten them once, and do not plan to rewrite them in the near future.  Those
+looking to _parse and convert_ many dates at once could look at \pkg{anytime}
+\citep{CRAN:anytime} where we use the Boost parser, or similar approaches using
+the C++ headers-only libraries in packages \pkg{RcppCCTZ} \citep{CRAN:RcppCCTZ}
+\pkg{RcppDate} \citep{CRAN:RcppDate}. We are not likely to carry this over to
+the \pkg{Rcpp} package as there are advantages in remaining dependency-free.