Is there a way I can replace a switch statement with actions by using a dictionary and some other code?

Question

Here is what my app has:

private void saveInDatabase(string key, string value)   

 switch (key)
 {
   case "a":
      def = Helpers.Utils.listOfDoubleFromString(value);
      break;
   case "b":
      chi = int.Parse(value);
      break;
            ....
   }

Is there a way that I could use a dictionary like this to decide what actions happen with the different case values?

   {"a", () => def = Helpers.Utils.listOfDoubleFromString(value)},
   {"b", () => chi = int.Parse(value)},

My app has a large number of these case statements so I am interested to know if I could replace them by setting up a dictionary and then some more code.

It's possible to map a key to a Func but how would you know what the return type is going to be? `dict[key](value);` — ChiefTwoPencils, Aug 19 '20 at 16:22
Sorry, I made a mistake when trying the mapping. I need to return to different things like def or chi. — Alan2, Aug 19 '20 at 16:28
And def and chi are available when you build the dictionary? — ChiefTwoPencils, Aug 19 '20 at 16:29
https://stackoverflow.com/questions/126409/ways-to-eliminate-switch-in-code — vin, Aug 19 '20 at 16:32
You'd have to create the dictionary in the method in order to capture those variables assuming they are local. Then it's just a `Dictionary`. — juharr, Aug 19 '20 at 16:40
You use a dictionary to reduce the search time from N/2 to a has which is log(N). Using a dictionary here where you need to search for ranges will not help unless you can map data to a BIN. For example it you have floating point numbers and can round number to an integer than a dictionary will speed up results. — jdweng, Aug 19 '20 at 16:40

score 1 · Accepted Answer · answered Aug 19 '20 at 16:54

1

I mean you pretty much got it:

string def;
int chi;

var map = new Dictionary<string, Action<string>>
{
    ["a"] = value => def = Helpers.Utils.listOfDoubleFromString(value),
    ["b"] = value => chi = int.Parse(value),
};

map[key](value);

answered Aug 19 '20 at 16:54

Blindy

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It is not so clear what the asker wants. You let your lambdas capture `def` and `chi` which are defined in a "containing scope", but not catch `value`. Depending on what `value` is, it may also be captured, and then you would have `Action` instead of `Action`. If you use your approach, maybe rename the string parameter in the lambdas to just `v`, but keep `value` in the invocation in the last line. – Jeppe Stig Nielsen Aug 19 '20 at 17:09
@Blindy - Could this be changed to Dictionary ? I have no need to capture any value. – Alan2 Aug 19 '20 at 17:14
@Alan2, but if you make it an `Action` you'll have to capture `value`; how else would you be able to use it? – ChiefTwoPencils Aug 19 '20 at 17:22
@Alan2, As you wish, if `value` is a field for example, it could be curried over instead of explicitly sent. These are the kinds of details that become clearer with actual code samples, instead of `int.Parse`. – Blindy Aug 19 '20 at 17:27
Helpers.Utils.listOfDoubleFromString(value) and intParse(value) are copied from the application code. Variable names def and chi are just short versions of longer variable names that are defined like App.CM.Selectedconf.newChi.delays. value is a parameter passed into the method where the switch appears. – Alan2 Aug 19 '20 at 17:37

Is there a way I can replace a switch statement with actions by using a dictionary and some other code?

1 Answers1