I have a single data structure that holds a relatively small amount of objects (ca. 1500) and several methods that are acting on it. Is there a programming pattern to iterate the methods over the data instead of writing significantly more boilerplate code?
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- LINQ allows you to work on collections while abstracting the boilerplate code. I suggest you to read this article by Martin Fowler (some of his examples are in C#).Spotted– Spotted2015-09-28 09:14:15 +00:00Commented Sep 28, 2015 at 9:14
- Do the methods all have the same parameters and return values? Or does the result of one method get sent to the next? Example code could help.Kasey Speakman– Kasey Speakman2015-09-28 14:04:11 +00:00Commented Sep 28, 2015 at 14:04
- The methods have all the same parameters and return valuesnarain– narain2015-09-28 14:14:46 +00:00Commented Sep 28, 2015 at 14:14
- 1please don't cross-post: stackoverflow.com/questions/32819062/…gnat– gnat2015-09-28 22:35:43 +00:00Commented Sep 28, 2015 at 22:35
- A little more information about your use case would be helpful. Please see how to ask a good question.Jay Elston– Jay Elston2015-09-29 00:51:03 +00:00Commented Sep 29, 2015 at 0:51
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1 Answer
I don't think there is a design pattern for this. It's much too simple to be a pattern, I believe.
You have a list of objects and a list of functions, and you want the cartesian product of those two lists, e.g.
objects := [10, 20, 30] functions := [add1, subtract1] product := functions.product(objects) // product looks like this: // [(add1, 10), (subtract1, 10), (add1, 20), (subtract1, 20), (add1, 30), (subtract1, 30)] product.map((fn, o) => fn(o)) // => [11, 9, 21, 19, 31, 29] In C#, it would look a bit like this (I don't really know C#, so take it with a grain of salt):
using System; using System.Collections.Generic; using System.Linq; class Prog { static int add1(int i) => i + 1; static int sub1(int i) => i - 1; public static void Main(string[] args) { var objs = new List<int> { 10, 20, 30 }; var funs = new List<Func<int, int>> { add1, sub1 }; var result = from obj in objs from fun in funs select fun(obj); result.ToList().ForEach(Console.WriteLine); // 11 // 9 // 21 // 19 // 31 // 29 } } 
- add1/sub1 would be more like
static int add1(int i) { return i + 1 }orstatic Func<int, int> add1 = i => i + 1;Kasey Speakman– Kasey Speakman2015-09-29 00:42:25 +00:00Commented Sep 29, 2015 at 0:42 - Why? The OP explicitly talked about methods, your second suggestion is a field, not a method. And your first suggestion is exactly what I wrote, only more verbose.Jörg W Mittag– Jörg W Mittag2015-09-29 06:57:59 +00:00Commented Sep 29, 2015 at 6:57
- @KaseySpeakman That is a new C# 6.0 syntax.svick– svick2015-09-29 07:25:57 +00:00Commented Sep 29, 2015 at 7:25
- @svick Oh. Jörg W Mittag: My bad. I thought you made a mistake since you said you didn't know C# well. I haven't use this new fangled syntax yet.Kasey Speakman– Kasey Speakman2015-09-29 13:14:25 +00:00Commented Sep 29, 2015 at 13:14