enumerator

问题 I'm having a problem with a Windows Form application I'm building in C#. The error is stating "foreach statement cannot operate on variables of type 'CarBootSale.CarBootSaleList' because 'CarBootSale.CarBootSaleList' does not contain a public definition for 'GetEnumerator'". I can't seem to understand what is causing this. This is the code that is throwing up the error: List<CarBootSaleList> Sortcarboot = new List<CarBootSaleList>(); foreach (CarBootSale c in carBootSaleList) { if (c.Charity

问题 Friends, please I need help with this explanation: In the Ruby code below, what condition termites the loop do? It's supposed to be an infinite loop, but, how does it terminate? # Ruby code fib = Enumerator.new do |y| a = b = 1 loop do y << a a, b = b, a + b end end p fib.take(10) # => [1, 1, 2, 3, 5, 8, 13, 21, 34, 55] Your contributions will be highly appreciated. 回答1: (Source: https://rossta.net/blog/infinite-sequences-in-ruby.html) The way you have implemented the function fib allows it

问题 I want to create an enumerator for external iteration via next that is clone -able, so that the clone retains the current enumeration state. As an example, let's say I have a method that returns an enumerator which yields square numbers: def square_numbers return enum_for(__method__) unless block_given? n = d = 1 loop do yield n d += 2 n += d end end square_numbers.take(10) #=> [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] And I want to enumerate the first 5 square numbers, and for each value, print

问题 I want to create an enumerator for external iteration via next that is clone -able, so that the clone retains the current enumeration state. As an example, let's say I have a method that returns an enumerator which yields square numbers: def square_numbers return enum_for(__method__) unless block_given? n = d = 1 loop do yield n d += 2 n += d end end square_numbers.take(10) #=> [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] And I want to enumerate the first 5 square numbers, and for each value, print

问题 Suppose I have an object: obj = Object.new #<Object:0x00007fbe36b4db28> And I convert it to an Enumerator: obj_enum = obj.to_enum #<Enumerator: #<Object:0x00007fbe36b4db28>:each> Now I want to get my object back from the enumerator. I found a way to do it, but it seems unnecessarily abstruse (not to mention pretty fragile): extracted_obj = ObjectSpace._id2ref( obj_enum.inspect.match(/0x[0-9a-f]*/).values_at(0)[0].to_i(16)/2 ) p obj.equal? extracted_obj # => true In case it isn't clear, I'm

问题 Suppose I have an object: obj = Object.new #<Object:0x00007fbe36b4db28> And I convert it to an Enumerator: obj_enum = obj.to_enum #<Enumerator: #<Object:0x00007fbe36b4db28>:each> Now I want to get my object back from the enumerator. I found a way to do it, but it seems unnecessarily abstruse (not to mention pretty fragile): extracted_obj = ObjectSpace._id2ref( obj_enum.inspect.match(/0x[0-9a-f]*/).values_at(0)[0].to_i(16)/2 ) p obj.equal? extracted_obj # => true In case it isn't clear, I'm

问题 To implement an interface member, the corresponding member of the implementing class must be public. source: Interfaces (C# Programming Guide) I know it works if its private, but i would like to understand why it can not be public ? 回答1: When implemented explicitly interface methods are public by default and that's why you cannot use access modifiers. A quote from msdn.com : When a member is explicitly implemented, it cannot be accessed through a class instance, but only through an instance

问题 This is typical ForEach container behaviour: However, if I do whats shown in the image below, the Execute SQL task never executes, how can i do this behaviour? I do not have to use ForEach container if some other type of container will allow me to do this. The for each loop essentially loops through files in multiple subdirectories in a folder. Based on which folder the loop is in, it populates a variable. this variable is used in the connectors from "some script" task to "task a" and "task b

问题 This is a spin-off question based on Eric Lippert's answer on this question. I would like to know why the C# language is designed not being able to detect the correct interface member in the following specific case. I am not looking on feedback whether designing a class this way is considered best practice. class Turtle { } class Giraffe { } class Ark : IEnumerable<Turtle>, IEnumerable<Giraffe> { public IEnumerator<Turtle> GetEnumerator() { yield break; } // explicit interface member

问题 All string.Split methods seems to return an array of strings ( string[] ). I'm wondering if there is a lazy variant that returns an IEnumerable<string> such that one for large strings (or an infinite length IEnumerable<char> ), when one is only interested in a first subsequences, one saves computational effort as well as memory. It could also be useful if the string is constructed by a device/program (network, terminal, pipes) and the entire strings is thus not necessary immediately fully