yinung at Gmail schrieb: > Dear all, > > I tested the User-defined functions and found some potential errors. > For example, my function is: > > <script> > function test (series y, int order[0:2:1], string option[null]) > if option="nc" > printf "%s\n","empty" > else > printf "%s\n","no options" > end if > end function > </script> > > the argument, string option[null], above should indicate that the > "option" string should be optional. > > After normally processing it as a package, I execute this function via > GUI (the same via command line). If I choose the default "null" as > automatically specified by gretl, I got an error: > > "The symbol 'otion' is undefined... error evaluating 'if' "
Maybe 'undefined' is a little misleading, but otherwise I think this part of gretl's behavior is ok, at least from what I'm used to in other languages: 'null' is not a string type and what the result of the comparison of 'null' and the string "nc" should be is not obvious IMHO. I think there is a isstring() function in gretl that could be used here. > > If I type any other strings, it works as normal. > If I give no string at all in the text box, gretl tells me: > > "Argument 3 (option) is missing" I agree this looks like a bug. -sven
