问题描述
What is the most efficient way to create a constant (never changes at runtime) mapping of strings to ints?
I've tried using a const Dictionary, but that didn't work out.
I could implement a immutable wrapper with appropriate semantics, but that still doesn't seem totally right.
For those who have asked, I'm implementing IDataErrorInfo in a generated class and am looking for a way to make the columnName lookup into my array of descriptors.
I wasn't aware (typo when testing! d'oh!) that switch accepts strings, so that's what I'm gonna use. Thanks!
Creating a truly compile-time generated constant dictionary in C# is not really a straightforward task. Actually, none of the answers here really achieve that.
There is one solution though which meets your requirements, although not necessarily a nice one; remember that according to the C# specification, switch-case tables are compiled to constant hash jump tables. That is, they are constant dictionaries, not a series of if-else statements. So consider a switch-case statement like this:
switch (myString)
{
case "cat": return 0;
case "dog": return 1;
case "elephant": return 3;
}
This is exactly what you want. And yes, I know, it's ugly.
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