Ray Dillinger scripsit: > Extending it to "any true value," on the other hand, would be > counterproductive because that would not allow you to directly give > the wide variety of more specific (success or) failure values that the > local OS is prepared to interpret.
I agree. > On the gripping hand, I have one proposed extension that I think is > more needful and useful. I think that the standard should state that > calling exit with any error-object as a value causes your program to > signal an exit with failure to the local OS. I have filed ticket #374 to treat *any* uninterpretable object as #f. > The current draft does NOT now specify the "meaning" of any argument > other than #f. It could specify #t, without causing any problems, > but I don't think that really adds much value apart from being more > tastefully symmetric. The advantage of defining #t for success is that you can say (exit (= error-count 0)) and the Right Thing happens. > As I read this, [correct but lengthy summary snipped] > [A] few words clarifying the rationale could help prevent > misunderstandings; otherwise someone might map *every* argument other > than #f to "success" and lose the power to pass meaningful specific > values to the OS. I think the sentence "If an argument is supplied, the exit procedure should translate the argument into an appropriate exit value for the operating system" is sufficiently clear. > However, I think it could make an additional useful requirement. It > could promise to signal an error exit when passed an error-object. I think that #374 subsumes this; surely no OS will expect a complex object like an error-object, which has a string and a list of arbitrary Scheme objects inside. > Error-objects, surely, are a category of things that can be expected > to come in flavors at least roughly matching an operating system's > categories of recognized program error types. I doubt that. In any case, Windows/Posix systems, unlike VMS, do not have standardized meanings for error codes. But I'm willing to be persuaded that there is a natural and universal mapping between error objects and process exit codes that ought to be standardized. I'm just not persuaded yet. -- John Cowan [email protected] "Not to know The Smiths is not to know K.X.U." --K.X.U. _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
