I think the main benefit is to be able to control what shows up when enumerating an object’s properties, such as for in or Object.keys(). MDN explains it well with Object.defineProperty: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/Object/defineProperty So normally, when people want to add a method to Object, such as a polyfill for some method not supported in old browsers, … Read more
Not in ruby but in ActiveSupport: characters = [“Konata”, “Kagami”, “Tsukasa”] “Konata”.in?(characters) # => true
You add: using System.Linq; at the top of your source and make sure you’ve got a reference to the System.Core assembly. Count() is an extension method provided by the System.Linq.Enumerable static class for LINQ to Objects, and System.Linq.Queryable for LINQ to SQL and other out-of-process providers. EDIT: In fact, using Count() here is relatively inefficient … Read more
ar = [{“Vegetable”=>10}, {“Vegetable”=>5}, {“Dry Goods”=>3}, {“Dry Goods”=>2}] p ar.inject{|memo, el| memo.merge( el ){|k, old_v, new_v| old_v + new_v}} #=> {“Vegetable”=>15, “Dry Goods”=>5} Hash.merge with a block runs the block when it finds a duplicate; inject without a initial memo treats the first element of the array as memo, which is fine here.
The Zip operator merges the corresponding elements of two sequences using a specified selector function. var letters= new string[] { “A”, “B”, “C”, “D”, “E” }; var numbers= new int[] { 1, 2, 3 }; var q = letters.Zip(numbers, (l, n) => l + n.ToString()); foreach (var s in q) Console.WriteLine(s); Ouput A1 B2 C3
An enumerable property is one that can be included in and visited during for..in loops (or a similar iteration of properties, like Object.keys()). If a property isn’t identified as enumerable, the loop will ignore that it’s within the object. var obj = { key: ‘val’ }; console.log(‘toString’ in obj); // true console.log(typeof obj.toString); // “function” … Read more
It’s certainly not a bug. It’s behaving exactly as documented: true if every element of the source sequence passes the test in the specified predicate, or if the sequence is empty; otherwise, false. Now you can argue about whether or not it should work that way (it seems fine to me; every element of the … Read more
AsEnumerable() is effectively a cast to IEnumerable<T>, which makes member resolution find members of Enumerable instead of Queryable. It’s usually used when you want to force part of a query to run as SQL (or similar), and the remainder to run using LINQ to Objects. See my Edulinq blog post on it for more information. … Read more
Array#each executes the given block for each element of the array, then returns the array itself. Array#map also executes the given block for each element of the array, but returns a new array whose values are the return values of each iteration of the block. Example: assume you have an array defined thusly: arr = … Read more
The collection used in foreach is immutable. This is very much by design. As it says on MSDN: The foreach statement is used to iterate through the collection to get the information that you want, but can not be used to add or remove items from the source collection to avoid unpredictable side effects. If … Read more