lambda

问题 Why does the following happen with Python's lambdas (in both Python 2 and 3)? >>> zero = lambda n: n is 0 >>> zero(0) True >>> zero = lambda n: n is 0.0 >>> zero(0.0) False 回答1: The most common Python implementation store a number of small integers as "constant" or "permanent" objects in a pre-allocated array: see the documentation. So, these numbers can be recongized as identical objects using the is operator. This is not done for floats. If you were to compare the numbers using the equality

问题 I am trying to get a Delegate from a MethodInfo object that has Output Parameters. My code follows: static void Main(string[] args) { MethodInfo m = typeof(Program).GetMethod("MyMethod2"); IEnumerable<Type> paramsTypes = m.GetParameters().Select(p => p.ParameterType); Type methodType = Expression.GetDelegateType(paramsTypes.Append(m.ReturnType).ToArray()); Delegate d = m.CreateDelegate(methodType); Action a = (Action)d; a(); } I'm getting is a System.InvalidCastException: Unable to cast

问题 The following toy function ordinarily takes two input variables: f = lambda u1, u2 : (u1*u2)*(u1**2+u2**2) but can scale beyond the bivariate case to higher dimensions: if dim == 2: f = lambda u1, u2 : (u1*u2)*(u1**2+u2**2) if dim == 3: f = lambda u1, u2, u3 : (u1*u2*u3)*(u1**2+u2**2+u3**2) if dim == 4: f = lambda u1, u2, u3, u4 : (u1*u2*u3*u4)*(u1**2+u2**2+u3**2+u4**2) How can the lambda function be written so that it can expand itself in the call lambda u1, u2, u3, u4, ... as well as the

问题 (with C# 3.0 and VS 2008). Doing MVVM WPF stuff you often write properties like this: public bool MyProperty { get{return _myProperty;} set{ if(_myProperty == value)return; _myProperty = value; RaisePropertyChanged("MyProperty"); } } Doing TDD I often end up writing tests such as: [Test] public void MyPropertyRaisesPropertyChangedWhenChanged(){ var mySUT = CreateSUT(); bool eventRaised = false; string propName = ""; mySUT.PropertyChanged += (s,e)=>{eventRaised = true;propName = e.PropertyName

问题 (with C# 3.0 and VS 2008). Doing MVVM WPF stuff you often write properties like this: public bool MyProperty { get{return _myProperty;} set{ if(_myProperty == value)return; _myProperty = value; RaisePropertyChanged("MyProperty"); } } Doing TDD I often end up writing tests such as: [Test] public void MyPropertyRaisesPropertyChangedWhenChanged(){ var mySUT = CreateSUT(); bool eventRaised = false; string propName = ""; mySUT.PropertyChanged += (s,e)=>{eventRaised = true;propName = e.PropertyName

问题 I tried to upgrade one of my lambda but can't make it work... so I have a lambda to manage my stripe payment, everything work fine. I want to send a message to SQS when a payment is OK. You can see my lambda function below : const stripe = require('stripe')("sk_test_xXxXxXxXxX"); const ApiBuilder = require('claudia-api-builder'); const querystring = require('querystring'); var api = new ApiBuilder(); var AWS = require('aws-sdk'); var sqs = new AWS.SQS({region : 'eu-west-1'}); var queueUrl =

问题 Hello Community i am aware of this might be a possible duplicate. How do I dynamically create an Expression<Func<MyClass, bool>> predicate from Expression<Func<MyClass, string>>? https://www.strathweb.com/2018/01/easy-way-to-create-a-c-lambda-expression-from-a-string-with-roslyn/ How to create a Expression.Lambda when a type is not known until runtime? Creating expression tree for accessing a Generic type's property There are obviously too many resources. I am still confused though. Could

问题 Every time I have a syntax error or I just want to send a custom error in my AWS Lambda function, I get the same 502 Bad Gateway response (Internal server error). I tried that simple code: module.exports.saveImage = (event, context, callback) => { callback("the sky is falling!"); // also tried sending new Error("the sky is falling!") } And still getting the same "Internal server error" response instead of the defined one. This is my function in the serverless.yml file: saveImage: handler:

问题 I'm trying to iterate over JavaPairRDD and perform some calculations with keys and values of JavaPairRDD. Then output result for each JavaPair into processedData list. What I already tried: make variables, that I use inside of lambda function static. make methods, that I call from lambda foreach loop static. added implements Serializable Here is my code: List<String> processedData = new ArrayList<>(); JavaPairRDD<WebLabGroupObject, Iterable<WebLabPurchasesDataObject>> groupedByWebLabData

问题 I have a method to be called. public void RecordConversation(ref ChannelResource cr) { VoiceResource RecordResource = TServer.GetVoiceResource(); RecordResource.MaximumTime = 6000; RecordResource.MaximumSilence = 6000; RecordResource.TerminationDigits = ""; } To call it in a thread Thread recordThread = new Thread(() => RecordConversation(ref ChanResource)); recordThread.Start(); Of course we get an error. Cannot use ref or out parameter 'ChanResource' inside an anonymous method, lambda