IronScheme: How do you 'or' enumeration entries

Question

How do you 'or' enum entries in IronScheme, ex:

(import                                                                                                                                               
  (rnrs)                                                                                                                                               
  (ironscheme clr))                                                                                                                                    

(clr-using System.Reflection)                                                                                                                         

(define public-class-attributes                                                                                                                       
  (bitwise-ior                                                                                                                                        
    (clr-static-field-get                                                                                                                              
      TypeAttributes Public)                                                                                                                            
    (clr-static-field-get                                                                                                                              
      TypeAttributes Class)))                                                                                                                           

(display public-class-attributes)

This causes an error, I haven't found an alternative in the documentation.

Hi. This is not directly possible in IronScheme as enums are not seen as integer types. IIRC though, there is a way to emulate this using a list of symbols as a argument when using `clr-call`. I will see if I have an existing example. — leppie, Aug 24 '15 at 14:18

score 2 · Accepted Answer · answered Aug 25 '15 at 12:25

I am not sure what your use case is, but as mentioned in the comment, when using clr-call a list of symbols can be used for an OR'd enum. Example here.

Internally, the compiler will wrap the list with a call to Helpers.SymbolToEnum<T>().

Note: The case is ignored.

To illustrate in a small example:

C# code:

[Flags]
enum Foo
{
  Bar = 1,
  Baz = 2
}

class AType 
{
  static void Kazaam(Foo foo) { ... }
}

Scheme code:

; same as Bar | Baz
(clr-static-call AType Kazaam '(Bar Baz))

; single value
(clr-static-call AType Kazaam 'Baz)
; same thing
(clr-static-call AType Kazaam '(Baz))

; no value (iow zero)
(clr-static-call AType Kazaam '())

If these are just simple flag, lists should suffice, else you can redefine the enum as an enum-set in Scheme which allows many set operations. Finally, you just use enum-set->list to get the list to pass as an argument as shown above.

IronScheme: How do you 'or' enumeration entries

1 Answers1