Active bindings are another option (?makeActiveBinding). It might be worth revisiting how promises are evaluated to see if at elast a more sensible error message can be achieved, but making sure any changes do not affect performance will be tricky.
Best, luke On Wed, 18 Oct 2006, Duncan Temple Lang wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > Hi Simon. > > One approach is RObjectTables. This provides a way to > customize how variables are accessed/assigned in > an environment and so allows an operation to do something > to compute the value of a variable while still allowing > it to be used as a variable rather than an explicit function > call by the user. > > Otherwise, Seth's suggestion of an accessor function is the natural way. > This does arise often and we need an extensible SEXP facility > that allows us to capture some of the idioms that continue to arise. > > D. > > Simon Urbanek wrote: >> Martin, >> >> On Oct 17, 2006, at 11:43 PM, Martin Morgan wrote: >> >> >>> I believe the technique is to create an environment in the >>> namespace, and then to access that through functions: >>> >> >> >> thanks, but this is not what I want (the symbols in the environment >> are invisible outside) and it has nothing to do with the question I >> posed: as I was saying in the previous e-mail the point is to have >> exported variables in a namespace, but their value is known only >> after the namespace was attached (to be precise I'm talking about >> rJava here and many variables are valid only after the VM was >> initialized - using them before is an error). I have an ugly work- >> around for that as well, the question was whether promises could be >> used for that purpose as a more clean solution and the answer appears >> to be no - at least for R <=2.4.0. >> >> Thanks, >> Simon >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > - -- > Duncan Temple Lang [EMAIL PROTECTED] > Department of Statistics work: (530) 752-4782 > 4210 Mathematical Sciences Building fax: (530) 752-7099 > One Shields Ave. > University of California at Davis > Davis, > CA 95616, > USA > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.3 (Darwin) > > iD8DBQFFNksN9p/Jzwa2QP4RAjXYAJ0cbGzw6IsCU62RWGxHDS7v1E4jzwCeOWSz > HGMaKhRjidss+7cu3gok2YU= > =3XhK > -----END PGP SIGNATURE----- > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Luke Tierney Chair, Statistics and Actuarial Science Ralph E. Wareham Professor of Mathematical Sciences University of Iowa Phone: 319-335-3386 Department of Statistics and Fax: 319-335-3017 Actuarial Science 241 Schaeffer Hall email: [EMAIL PROTECTED] Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
