"is" c# multiple options

Question

return (
      Page is WebAdminPriceRanges ||
      Page is WebAdminRatingQuestions
);

Is there a way to do it like:

return (
    Page is WebAdminPriceRanges || WebAdminRatingQuestions
);

The is operator takes two operands in C#. That is really all there is to say. However, with a bit of fancy, "could be" similar to `IsAnyOf(x, myListOfTypes)` (it would use `IsAssignableFrom` internally though, not `is`.) In fact, I have seen this done before on SO. (Try searching for `IsAssingableFrom`.) — , May 23 '12 at 08:40
e.g. http://stackoverflow.com/questions/3013694/use-of-isassignablefrom-and-is-keyword-in-c-sharp — , May 23 '12 at 08:42

score 4 · Answer 1 · answered May 23 '12 at 08:38

No, such syntax is not possible. The is operator requires 2 operands, the first is an instance of an object and the second is a type.

You could use GetType():

return new[] { typeof(WebAdminPriceRanges), typeof(WebAdminRatingQuestions) }.Contains(Page.GetType());

score 4 · Answer 2 · answered May 23 '12 at 08:38

Not really. You can look for the Type instance inside a collection, but that doesn't account for the implicit conversions that is performs; for example, is also detects if the type is a base of the instance it operates on.

Example:

var types = new[] {typeof(WebAdminPriceRanges), typeof(WebAdminRatingQuestions)};

// this will return false if Page is e.g. a WebAdminBase
var is1 = types.Any(t => t == Page.GetType());

// while this will return true
var is2 = Page is WebAdminPriceRanges || Page is WebAdminRatingQuestions;

score 2 · Accepted Answer · answered May 23 '12 at 08:39

2

No. The first way you specified is the only reasonable way to do this.

answered May 23 '12 at 08:39

tomfanning

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score 1 · Answer 4 · answered May 23 '12 at 08:38

1

No, C# is not the English language, you cannot omit one operand from a two-operand operation.

answered May 23 '12 at 08:38

Tudor

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score 0 · Answer 5 · answered May 23 '12 at 08:38

No, you can not do this.

if your intent is return a Page, only if it is of type WebAdminPriceRanges or WebAdminRatingQuestions , you can easily do it with if.

For example:

if(Page is WebAdminPriceRanges || Page is WebAdminRatingQuestions)
   return Page;
return null;

Assuming that Page is a reference type or at least nullable value type

score 0 · Answer 6 · answered May 23 '12 at 08:49

0

The other answers are true, but while I'm not sure where is fits in operator precedence. If the is operator is lower than the logical-or operator, you would be or-ing two classes together which is meaningless.

answered May 23 '12 at 08:49

kenny

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"is" c# multiple options

6 Answers6