On Thu, 18 Oct 2007, andreas.rosenblad(a)ltv.se wrote: > Currently, when writing a user-defined function, the parameters > can be of six types: bool (scalar variable acting as a Boolean > switch), int (scalar variable acting as an integer), scalar > (scalar variable), series (data series), list (named list of > series) and matrix (named matrix or vector). > > To make it easier to write a user-defined function and make it > more flexible I would appreciate if three other parameter types > could be included: > > * "discrete" (a data series with only discrete values) > * "proportion" or "quantile" (a scalar which value is between 0 and 1) > * "select" (providing a list of alternatives to select from). > > As it is now, the first two parameter types, "discrete" and > "proportion", could be input to the function as "series" and > "scalar", and the user has to let the function check if they are > discrete or between 0 and 1. It would be nice if it instead was > automatically checked already at the input by the parameter type >

"proportion" would be quite easy to do;

"discrete" less so. The trouble is that I don't think "discrete" denotes a well-defined data type. It would, I suppose, if we restricted it to integer values, but some people think that's too restrictive. As things stand, I think it's up to the function writer to decide what counts as discrete in any given context.

> For the third parameter type, "select", I imagine writing e.g. > function(select rejectionregion["two sided","one sided > lower","one sided upper"]) would in the GUI produce a drop-down > list for this

That's definitely a nice idea. We could have a go at that after the 1.6.6 release.