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  • Java Magazine????7???

    - by sasa
    11?20??Java Magazine????7?????????? ?7???????????????? ?????Java DUKE’S CHOICE AWARDS BlueJ?????????????????????? Web??????????????????????????? Project Lambda??? Java HotSpot VM??????(2):????????????????? NIO.2??????·????API??? Java EE Connector Architecture 1.6 Payment API—JSR 229?? Oracle Berkeley DB Java Edition?Java API(???2) ???????JavaFX????????? Graal??? JavaFX Media API????????? ?????????????????????????????????????????? Java Magazone?????????Java??????????????Java Developer Newsletter???????????????????????????12?31?????????????1,000???Java??????Duke?????????????????????

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  • Imperative Programming v/s Declarative Programming v/s Functional Programming

    - by kaleidoscope
    Imperative Programming :: Imperative programming is a programming paradigm that describes computation in terms of statements that change a program state. In much the same way as the imperative mood in natural languages expresses commands to take action, imperative programs define sequences of commands for the computer to perform. The focus is on what steps the computer should take rather than what the computer will do (ex. C, C++, Java). Declarative Programming :: Declarative programming is a programming paradigm that expresses the logic of a computation without describing its control flow. It attempts to minimize or eliminate side effects by describing what the program should accomplish, rather than describing how to go about accomplishing it. The focus is on what the computer should do rather than how it should do it (ex. SQL). A  C# example of declarative v/s. imperative programming is LINQ. With imperative programming, you tell the compiler what you want to happen, step by step. For example, let's start with this collection, and choose the odd numbers: List<int> collection = new List<int> { 1, 2, 3, 4, 5 }; With imperative programming, we'd step through this, and decide what we want: List<int> results = new List<int>(); foreach(var num in collection) {     if (num % 2 != 0)           results.Add(num); } Here’s what we are doing: *Create a result collection *Step through each number in the collection *Check the number, if it's odd, add it to the results With declarative programming, on the other hand, we write the code that describes what you want, but not necessarily how to get it var results = collection.Where( num => num % 2 != 0); Here, we're saying "Give us everything where it's odd", not "Step through the collection. Check this item, if it's odd, add it to a result collection." Functional Programming :: Functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions.Functional programming has its roots in the lambda calculus. It is a subset of declarative languages that has heavy focus on recursion. Functional programming can be a mind-bender, which is one reason why Lisp, Scheme, and Haskell have never really surpassed C, C++, Java and COBOL in commercial popularity. But there are benefits to the functional way. For one, if you can get the logic correct, functional programming requires orders of magnitude less code than imperative programming. That means fewer points of failure, less code to test, and a more productive (and, many would say, happier) programming life. As systems get bigger, this has become more and more important. To know more : http://stackoverflow.com/questions/602444/what-is-functional-declarative-and-imperative-programming http://msdn.microsoft.com/en-us/library/bb669144.aspx http://en.wikipedia.org/wiki/Imperative_programming   Technorati Tags: Ranjit,Imperative Programming,Declarative programming,Functional Programming

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  • InternalsVisibleTo attribute and security vulnerability

    - by Sergey Litvinov
    I found one issue with InternalsVisibleTo attribute usage. The idea of InternalsVisibleTo attribute to allow some other assemblies to use internal classes\methods of this assembly. To make it work you need sign your assemblies. So, if other assemblies isn't specified in main assembly and if they have incorrect public key, then they can't use Internal members. But the issue in Reflection Emit type generation. For example, we have CorpLibrary1 assembly and it has such class: public class TestApi { internal virtual void DoSomething() { Console.WriteLine("Base DoSomething"); } public void DoApiTest() { // some internal logic // ... // call internal method DoSomething(); } } This assembly is marked with such attribute to allow another CorpLibrary2 to make inheritor for that TestAPI and override behaviour of DoSomething method. [assembly: InternalsVisibleTo("CorpLibrary2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100434D9C5E1F9055BF7970B0C106AAA447271ECE0F8FC56F6AF3A906353F0B848A8346DC13C42A6530B4ED2E6CB8A1E56278E664E61C0D633A6F58643A7B8448CB0B15E31218FB8FE17F63906D3BF7E20B9D1A9F7B1C8CD11877C0AF079D454C21F24D5A85A8765395E5CC5252F0BE85CFEB65896EC69FCC75201E09795AAA07D0")] The issue is that I'm able to override this internal DoSomething method and break class logic. My steps to do it: Generate new assembly in runtime via AssemblyBuilder Get AssemblyName from CorpLibrary1 and copy PublikKey to new assembly Generate new assembly that will inherit TestApi class As PublicKey and name of generated assembly is the same as in InternalsVisibleTo, then we can generate new DoSomething method that will override internal method in TestAPI assembly Then we have another assembly that isn't related to this CorpLibrary1 and can't use internal members. We have such test code in it: class Program { static void Main(string[] args) { var builder = new FakeBuilder(InjectBadCode, "DoSomething", true); TestApi fakeType = builder.CreateFake(); fakeType.DoApiTest(); // it will display: // Inject bad code // Base DoSomething Console.ReadLine(); } public static void InjectBadCode() { Console.WriteLine("Inject bad code"); } } And this FakeBuilder class has such code: /// /// Builder that will generate inheritor for specified assembly and will overload specified internal virtual method /// /// Target type public class FakeBuilder { private readonly Action _callback; private readonly Type _targetType; private readonly string _targetMethodName; private readonly string _slotName; private readonly bool _callBaseMethod; public FakeBuilder(Action callback, string targetMethodName, bool callBaseMethod) { int randomId = new Random((int)DateTime.Now.Ticks).Next(); _slotName = string.Format("FakeSlot_{0}", randomId); _callback = callback; _targetType = typeof(TFakeType); _targetMethodName = targetMethodName; _callBaseMethod = callBaseMethod; } public TFakeType CreateFake() { // as CorpLibrary1 can't use code from unreferences assemblies, we need to store this Action somewhere. // And Thread is not bad place for that. It's not the best place as it won't work in multithread application, but it's just a sample LocalDataStoreSlot slot = Thread.AllocateNamedDataSlot(_slotName); Thread.SetData(slot, _callback); // then we generate new assembly with the same nameand public key as target assembly trusts by InternalsVisibleTo attribute var newTypeName = _targetType.Name + "Fake"; var targetAssembly = Assembly.GetAssembly(_targetType); AssemblyName an = new AssemblyName(); an.Name = GetFakeAssemblyName(targetAssembly); // copying public key to new generated assembly var assemblyName = targetAssembly.GetName(); an.SetPublicKey(assemblyName.GetPublicKey()); an.SetPublicKeyToken(assemblyName.GetPublicKeyToken()); AssemblyBuilder assemblyBuilder = Thread.GetDomain().DefineDynamicAssembly(an, AssemblyBuilderAccess.RunAndSave); ModuleBuilder moduleBuilder = assemblyBuilder.DefineDynamicModule(assemblyBuilder.GetName().Name, true); // create inheritor for specified type TypeBuilder typeBuilder = moduleBuilder.DefineType(newTypeName, TypeAttributes.Public | TypeAttributes.Class, _targetType); // LambdaExpression.CompileToMethod can be used only with static methods, so we need to create another method that will call our Inject method // we can do the same via ILGenerator, but expression trees are more easy to use MethodInfo methodInfo = CreateMethodInfo(moduleBuilder); MethodBuilder methodBuilder = typeBuilder.DefineMethod(_targetMethodName, MethodAttributes.Public | MethodAttributes.Virtual); ILGenerator ilGenerator = methodBuilder.GetILGenerator(); // call our static method that will call inject method ilGenerator.EmitCall(OpCodes.Call, methodInfo, null); // in case if we need, then we put call to base method if (_callBaseMethod) { var baseMethodInfo = _targetType.GetMethod(_targetMethodName, BindingFlags.NonPublic | BindingFlags.Instance); // place this to stack ilGenerator.Emit(OpCodes.Ldarg_0); // call the base method ilGenerator.EmitCall(OpCodes.Call, baseMethodInfo, new Type[0]); // return ilGenerator.Emit(OpCodes.Ret); } // generate type, create it and return to caller Type cheatType = typeBuilder.CreateType(); object type = Activator.CreateInstance(cheatType); return (TFakeType)type; } /// /// Get name of assembly from InternalsVisibleTo AssemblyName /// private static string GetFakeAssemblyName(Assembly assembly) { var internalsVisibleAttr = assembly.GetCustomAttributes(typeof(InternalsVisibleToAttribute), true).FirstOrDefault() as InternalsVisibleToAttribute; if (internalsVisibleAttr == null) { throw new InvalidOperationException("Assembly hasn't InternalVisibleTo attribute"); } var ind = internalsVisibleAttr.AssemblyName.IndexOf(","); var name = internalsVisibleAttr.AssemblyName.Substring(0, ind); return name; } /// /// Generate such code: /// ((Action)Thread.GetData(Thread.GetNamedDataSlot(_slotName))).Invoke(); /// private LambdaExpression MakeStaticExpressionMethod() { var allocateMethod = typeof(Thread).GetMethod("GetNamedDataSlot", BindingFlags.Static | BindingFlags.Public); var getDataMethod = typeof(Thread).GetMethod("GetData", BindingFlags.Static | BindingFlags.Public); var call = Expression.Call(allocateMethod, Expression.Constant(_slotName)); var getCall = Expression.Call(getDataMethod, call); var convCall = Expression.Convert(getCall, typeof(Action)); var invokExpr = Expression.Invoke(convCall); var lambda = Expression.Lambda(invokExpr); return lambda; } /// /// Generate static class with one static function that will execute Action from Thread NamedDataSlot /// private MethodInfo CreateMethodInfo(ModuleBuilder moduleBuilder) { var methodName = "_StaticTestMethod_" + _slotName; var className = "_StaticClass_" + _slotName; TypeBuilder typeBuilder = moduleBuilder.DefineType(className, TypeAttributes.Public | TypeAttributes.Class); MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, MethodAttributes.Static | MethodAttributes.Public); LambdaExpression expression = MakeStaticExpressionMethod(); expression.CompileToMethod(methodBuilder); var type = typeBuilder.CreateType(); return type.GetMethod(methodName, BindingFlags.Static | BindingFlags.Public); } } remarks about sample: as we need to execute code from another assembly, CorpLibrary1 hasn't access to it, so we need to store this delegate somewhere. Just for testing I stored it in Thread NamedDataSlot. It won't work in multithreaded applications, but it's just a sample. I know that we use Reflection to get private\internal members of any class, but within reflection we can't override them. But this issue is allows anyone to override internal class\method if that assembly has InternalsVisibleTo attribute. I tested it on .Net 3.5\4 and it works for both of them. How does it possible to just copy PublicKey without private key and use it in runtime? The whole sample can be found there - https://github.com/sergey-litvinov/Tests_InternalsVisibleTo UPDATE1: That test code in Program and FakeBuilder classes hasn't access to key.sn file and that library isn't signed, so it hasn't public key at all. It just copying it from CorpLibrary1 by using Reflection.Emit

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  • Installing Fabric On Windows (Error No Module Called Readline)

    - by Jon
    I'm trying to use the Fabric 0.1.1 deploy tool (http://docs.fabfile.org/) on Windows and we're running into an issue with the readline module. I've been through various threads but can't seem to solve the issue. It's important because we can't deploy applications from Windows based machines. C:\Documents and Settings\dev\Desktop\deploy>fab Traceback (most recent call last): File "C:\python\Scripts\fab-script.py", line 8, in <module> load_entry_point('fabric==0.1.1', 'console_scripts', 'fab')() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 277, in load_entry_point File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 2180, in load_entry_point File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\pkg_resources.py" , line 1913, in load File "build\bdist.win32\egg\fabric.py", line 25, in <module> **ImportError: No module named readline** Installing the module results in: **easy_install readline** Searching for readline Reading http://pypi.python.org/simple/readline/ Reading http://www.python.org/ Best match: readline 2.6.4 Downloading http://pypi.python.org/packages/source/r/readline/readline-2.6.4.tar .gz#md5=7568e8b78f383443ba57c9afec6f4285 Processing readline-2.6.4.tar.gz Running readline-2.6.4\setup.py -q bdist_egg --dist-dir c:\docume~1\ji81b9~1.che \locals~1\temp\easy_install-pzkz1a\readline-2.6.4\egg-dist-tmp-szs2ps Traceback (most recent call last): File "C:\python\Scripts\easy_install-script.py", line 8, in <module> load_entry_point('setuptools==0.6c9', 'console_scripts', 'easy_install')() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1671, in main File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1659, in with_ei_usage File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 1675, in <lambda> File "c:\python\lib\distutils\core.py", line 152, in setup dist.run_commands() File "c:\python\lib\distutils\dist.py", line 975, in run_commands self.run_command(cmd) File "c:\python\lib\distutils\dist.py", line 995, in run_command cmd_obj.run() File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 211, in run File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 446, in easy_install File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 476, in install_item File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 655, in install_eggs File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 930, in build_and_install File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\comman d\easy_install.py", line 919, in run_setup File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 27, in run_setup File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 63, in run File "c:\python\lib\site-packages\setuptools-0.6c9-py2.6.egg\setuptools\sandbo x.py", line 29, in <lambda> File "setup.py", line 93, in <module> AttributeError: 'module' object has no attribute 'symlink' Has anybody solved this issue or can anybody suggest a workaround?

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  • Matrix addition in Scheme

    - by user285012
    I am trying to add a matrix and it is not working... (define (matrix-matrix-add a b) (map (lambda (row) (row-matrix-add row b)) a)) (define (row-matrix-add row matrix) (if (null? (car matrix)) '() (cons (add-m row (map car matrix)) (row-matrix-add row (map cdr matrix))))) (define (add-m row col) (if (null? col) 0 (+ (car row) (car col) (add-m (cdr row) (cdr col)))))

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  • Rails has_many with dinamyc :conditions

    - by Fabiano PS
    Hello! What I want is to create a Model that connects with other by a has_many in a dinamic way, without the foreing_key like this: has_many :faixas_aliquotas, :class_name => 'Fiscal::FaixaAliquota', :conditions => ["regra_fiscal = ?", ( lambda { return self.regra_fiscal } ) ] But I get the error: : SELECT * FROM "fis_faixa_aliquota" WHERE ("fis_faixa_aliquota".situacao_fiscal_id = 1 AND (regra_fiscal = E'--- !ruby/object:Proc {}')) Is my will makeable? I don't wanna black magic solution..

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  • Rails has_many with dynamic conditions

    - by Fabiano PS
    Hello! What I want is to create a Model that connects with another using a has_many association in a dynamic way, without the foreign key like this: has_many :faixas_aliquotas, :class_name => 'Fiscal::FaixaAliquota', :conditions => ["regra_fiscal = ?", ( lambda { return self.regra_fiscal } ) ] But I get the error: : SELECT * FROM "fis_faixa_aliquota" WHERE ("fis_faixa_aliquota".situacao_fiscal_id = 1 AND (regra_fiscal = E'--- !ruby/object:Proc {}')) Is this possible?

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  • Background color for Tk in Python

    - by olofom
    I'm writing a slideshow program with Tkinter, but I don't know how to change the background color to black instead of the standard light gray. How can this be done? import os, sys import Tkinter import Image, ImageTk import time root = Tkinter.Tk() w, h = root.winfo_screenwidth(), root.winfo_screenheight() root.overrideredirect(1) root.geometry("%dx%d+0+0" % (w, h)) root.focus_set() root.bind("<Escape>", lambda e: e.widget.quit()) image = Image.open(image_path+f) tkpi = ImageTk.PhotoImage(image) label_image = Tkinter.Label(root, image=tkpi) label_image.place(x=0,y=0,width=w,height=h) root.mainloop(0)

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  • Itertools group by functionality

    - by Nil
    I want to group by on dict key >>> x [{'a': 10, 'b': 90}, {'a': 20}, {'a': 30}, {'a': 10}] >>> [(name, list(group)) for name, group in groupby(x, lambda p:p['a'])] [(10, [{'a': 10, 'b': 90}]), (20, [{'a': 20}]), (30, [{'a': 30}]), (10, [{'a': 10}])] This must group on key 10 :(

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  • Move to next message

    - by demas
    I have a messages line this: message 1 answer 1.1 answer 1.1.1 answer 1.2 answer 1.3 massage 2 ... and I have the line in my .gnus.el: (global-set-key [f9] (lambda () (interactive) (gnus-summary-lower-score-by-subj-substr-temp))) When I select "message 1" and press F9 next lines: message1 answer 1.1 answer 1.1.1 answer 1.2 answer 1.3 change the score. But I need the selection move to next message (message 2) when I press F9. How can I get it?

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  • What are the benefits of using Boost.Phoenix?

    - by Denis Shevchenko
    Hello all! I can not understand what the real benefits of using Boost.Phoenix. When I use it with Boost.Spirit grammars, it's really useful: double_[ boost::phoenix::push_back( boost::phoenix::ref( v ), _1 ) ] When I use it for lambda functions, it's also useful and elegant: boost::range::for_each( my_string, if_ ( '\\' == arg1 ) [ arg1 = '/' ] ); But what are the benefits of everything else in this library? The documentation says: "Functors everywhere". I don't understand what is the good of it?

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  • Palindrome Golf

    - by Claudiu
    The goal: Any language. The smallest function which will return whether a string is a palindrome. Here is mine in Python: R=lambda s:all(a==b for a,b in zip(s,reversed(s))) 50 characters. The accepted answer will be the current smallest one - this will change as smaller ones are found. Please specify the language your code is in.

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  • PLT Scheme sort function

    - by Danny
    PLT Scheme guide says that it's implemented sort function is able to sort a list according to an extarcted value using a lambda function. link text The guide provides an unworking code example of this- (sort '(("aardvark") ("dingo") ("cow") ("bear")) #:key car string<?) Which returns an error. How is this function is supposed to be calles so that it will actually sort a list according to values calculated by a given function?

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  • will_paginate with named_scopes

    - by Lowgain
    I'm using will_paginate for pagination, which has been working well so far, except for this one thing. If I try to paginate a scope, for instance class User < ActiveRecord::Base named_scope :scope, lambda { etc } end User.scope.paginate({:page => params[:page], :per_page => 10}) That will tell me paginate is an undefined method. I'd rather not have to use a second solution for only this scope, is there something I can do here?

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  • Dynamic URL -> Controller mapping for routes in Rails

    - by Daniel Beardsley
    I would like to be able to map URLs to Controllers dynamically based on information in my database. I'm looking to do something functionally equivalent to this (assuming a View model): map.route '/:view_name', :controller => lambda { View.find_by_name(params[:view_name]).controller } Others have suggested dynamically rebuilding the routes, but this won't work for me as there may be thousands of Views that map to the same Controller

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  • Derivative of a Higher-Order Function

    - by Claudiu
    This is in the context of Automatic Differentiation - what would such a system do with a function like map, or filter - or even one of the SKI Combinators? Example: I have the following function: def func(x): return sum(map(lambda a: a**x, range(20))) What would its derivative be? What will an AD system yield as a result? (This function is well-defined on real-number inputs).

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  • Hidden features of C#3.5 [closed]

    - by xyz
    Possible Duplicate: Hidden Features of C#? Kindly donot mistake this question with Hidden Features of C#?. It is specific to C# 3.5 / dot net 3.5 I have figured out some(what I have used so far). They are as under 1) Linq 2(Objects, Sql, Xml) 2) Lambda expressions 3) Extention methods 4) Object initializers 5) Collection initialisers 6) Anonymous delegates 7)Automatic properties Please help me in finding out more. Thanks

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  • Rails: three most recent comments with unique users

    - by Dennis Collective
    what would I put in the named scope :by_unique_users so that I can do Comment.recent.by_unique_users.limit(3), and only get one comment per user? class User has_many :comments end class Comment belongs_to :user named_scope :recent, :order => 'comments.created_at DESC' named_scope :limit, lambda { |limit| {:limit => limit}} named_scope :by_unique_users end on sqlite named_scope :by_unique_user, :group = "user_id" works, but makes it freak out on postgres, which is deployed on production PGError: ERROR: column "comments.id" must appear in the GROUP BY clause or be used in an aggregate function

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  • Getting started with nbehave

    - by dotnetdev
    Hi, I am looking at using BDD, however, when evaluating the stories/conditions I write (using nBehave), how do I check if the story passes? Do I write another library with test methods? For example, if I want to test a site for having a link called "About", do I write a method which can check this and then another method in another class library which can call the method to check the link via lambda syntax and add the relevant test and bdd attributes? Thanks

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  • Code hot swapping in Erlang

    - by Roger Alsing
    I recently saw a video about Erlang on InfoQ, In that video one of the creators presented how to replace the behavior of a message loop. He was simply sending a message containing a lambda of the new version of the message loop code, which then was invoked instead of calling the old loop again. Is that code hot swapping in Erlang reffers to? Or is that some other more native feature?

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  • Rails: three most recent comments for unique users

    - by Dennis Collective
    class User has_many :comments end class Comment belongs_to :user named_scope :recent, :order => 'comments.created_at DESC' named_scope :limit, lambda { |limit| {:limit => limit}} named_scope :by_unique_users end what would I put in the :by_unique_users so that I can do Comment.recent.by_unique_users.limit(3), and only get one comment per user

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  • twisted reactor stops too early

    - by pygabriel
    I'm doing a batch script to connect to a tcp server and then exiting. My problem is that I can't stop the reactor, for example: cmd = raw_input("Command: ") # custom factory, the protocol just send a line reactor.connectTCP(HOST,PORT, CommandClientFactory(cmd) d = defer.Deferred() d.addCallback(lambda x: reactor.stop()) reactor.callWhenRunning(d.callback,None) reactor.run() In this code the reactor stops before that the tcp connection is done and the cmd is passed. How can I stop the reactor after that all the operation are finished?

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