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  • Does it ever make sense to make a fundamental (non-pointer) parameter const?

    - by Scott Smith
    I recently had an exchange with another C++ developer about the following use of const: void Foo(const int bar); He felt that using const in this way was good practice. I argued that it does nothing for the caller of the function (since a copy of the argument was going to be passed, there is no additional guarantee of safety with regard to overwrite). In addition, doing this prevents the implementer of Foo from modifying their private copy of the argument. So, it both mandates and advertises an implementation detail. Not the end of the world, but certainly not something to be recommended as good practice. I'm curious as to what others think on this issue. Edit: OK, I didn't realize that const-ness of the arguments didn't factor into the signature of the function. So, it is possible to mark the arguments as const in the implementation (.cpp), and not in the header (.h) - and the compiler is fine with that. That being the case, I guess the policy should be the same for making local variables const. One could make the argument that having different looking signatures in the header and source file would confuse others (as it would have confused me). While I try to follow the Principle of Least Astonishment with whatever I write, I guess it's reasonable to expect developers to recognize this as legal and useful.

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  • Javascript private member on prototype...

    - by Wilq32
    Well I tried to figure out is this possible in any way. Here is code: a=function(text) { var b=text; if (!arguments.callee.prototype.get) arguments.callee.prototype.get=function() { return b; } else alert('already created!'); } var c=new a("test"); // creates prototype instance of getter var d=new a("ojoj"); // alerts already created alert(c.get()) // alerts test alert(d.get()) // alerts test from context of creating prototype function :( As you see I tried to create prototype getter. For what? Well if you write something like this: a=function(text) { var b=text; this.getText=function(){ return b} } ... everything should be fine.. but in fact every time I create object - i create getText function that uses memory. I would like to have one prototypical function lying in memory that would do the same... Any ideas? EDIT: I tried solution given by Christoph, and it seems that its only known solution for now. It need to remember id information to retrieve value from context, but whole idea is nice for me :) Id is only one thing to remember, everything else can be stored once in memory. In fact you could store a lot of private members this way, and use anytime only one id. Actually this is satisfying me :) (unless someone got better idea). someFunc = function() { var store = new Array(); var guid=0; var someFunc = function(text) { this.__guid=guid; store[guid++]=text; } someFunc.prototype.getValue=function() { return store[this.__guid]; } return someFunc; }() a=new someFunc("test"); b=new someFunc("test2"); alert(a.getValue()); alert(b.getValue());

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  • How to extend a jquery ui widget ? (1.7)

    - by Jide
    I would like to create a custom version of the sortable widget. I have been searching for documentation, but could not find something really accurate. The best information I found was : http://jqueryui.pbworks.com/Widget-factory. I tried : $.widget("ui.customsortable", $.extend($.ui.sortable, { _init: function() { $.widget.prototype._init.apply(this, arguments); } })); But $.widget.prototype._init is not the function I want to call I guess since it is the $.widget prototype. Then, I tried something I read here and there : var _init = $.ui.sortable.prototype._init; $.widget("ui.customsortable", $.extend($.ui.sortable, { _init: function() { _init.apply(this, arguments); }, })); But : I can't believe I have to store all methods I want to override like this, it is so ugly. It throws an error ("this.refresh is not a function"), which means the refresh method does not exist. Does that mean I would have to recreate all methods I want to override ? What's the point of extending in that case ? Am I missing something here ? Thanks for your help !

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  • Django, url tag in template doesn't work: NoReverseMatch

    - by Lukasz Jocz
    I've encountered a problem with generating reverse url in templates in django. I'm trying to solve it since a few hours and I have no idea what the problem might be. URL reversing works great in models and views: # like this in models.py @models.permalink def get_absolute_url(self): return ('entry', (), { 'entry_id': self.entry.id, }) # or this in views.py return HttpResponseRedirect(reverse('entry',args=(entry_id,))) but when I'm trying to make it in template I get such an error: NoReverseMatch at /entry/1/ Reverse for ''add_comment'' with arguments '(1L,)' and keyword arguments '{}' not found. My file structure looks like this: project/ +-- frontend ¦   +-- models.py ¦   +-- urls.py ¦   +-- views.py +-- settings.py +-- templates ¦   +-- add_comment.html ¦   +-- entry.html +-- utils ¦   +-- with_template.py +-- wsgi.py My urls.py: from project.frontend.views import * from django.conf.urls import patterns, include, url urlpatterns = patterns('project.frontend.views', url(r'^entry/(?P<entry_id>\d+)/', 'entry', name="entry"), (r'^entry_list/', 'entry_list'), Then entry_list.html: {% extends "base.html" %} {% block content %} {% for entry in entries %} {% url 'entry' entry.id %} {% endfor %} {% endblock %} In views.py I have: @with_template def entry(request, entry_id): entry = Entry.objects.get(id=entry_id) entry.comments = entry.get_comments() return locals() where with_template is following decorator(but I don't think this is a case): class TheWrapper(object): def __init__(self, default_template_name): self.default_template_name = default_template_name def __call__(self, func): def decorated_func(request, *args, **kwargs): extra_context = kwargs.pop('extra_context', {}) dictionary = {} ret = func(request, *args, **kwargs) if isinstance(ret, HttpResponse): return ret dictionary.update(ret) dictionary.update(extra_context) return render_to_response(dictionary.get('template_name', self.default_template_name), context_instance=RequestContext(request), dictionary=dictionary) update_wrapper(decorated_func, func) return decorated_func if not callable(arg): return TheWrapper(arg) else: default_template_name = ''.join([ arg.__name__, '.html']) return TheWrapper(default_template_name)(arg) Do you have any idea, what may cause the problem? Great thanks in advance!

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  • Problems with video conversions through the web (local host)

    - by ron-d
    Hello, I get the following errors when I attempt video format conversions called from the local host: “An invalid media type was specified” for M4V to WMV conversions. “One or more arguments are invalid” for MP4 to WMV conversions. Here are the details of the problems: I’ve written a dll in C# that accepts videos in the formats AVI, WMV, M4V and MP4 and performs the following actions: Creates a copy of the input video in WMV format . Creates a WAV file of the input video audio portion. Creates a JPG image from a frame of the input video. I attached the dll to an ASP.NET web project that performs the dll actions. When tested through the developer studio, the actions are performed as intended for all formats. When I place the web project in place to be read when the local host is called through the web browser, the following behavior takes place: WMV format: All actions performed as intended. AVI format: Creates WMV file – OK Creates JPG image – OK Creates empty WAV file – problem. M4V format: Creates empty WAV file – problem. Does not create WMV file -problem Does not create JPG file –problem Throws me the error “An invalid media type was specified” MP4 format: Creates empty WAV file – problem. Does not create WMV file -problem Does not create JPG file –problem Throws me the error “One or more arguments are invalid” When I check their security property, all the files have the same permission access parameters (when I check their security property. Can anyone guide me as to how to solve these problems when the web project is called from the local host? Thank you.

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  • Detect Application Shutdown in C# NET?

    - by Michael Pfiffer
    I am writing a small console application (will be ran as a service) that basically starts a Java app when it is running, shuts itself down if the Java app closes, and shuts down the Java app if it closes. I think I have the first two working properly, but I don't know how to detect when the .NET application is shutting down so that I can shutdown the Java app prior to that happening. Google search just returns a bunch of stuff about detecting Windows shutting down. Can anyone tell me how I can handle that part and if the rest looks fine? namespace MinecraftDaemon { class Program { public static void LaunchMinecraft(String file, String memoryValue) { String memParams = "-Xmx" + memoryValue + "M" + " -Xms" + memoryValue + "M "; String args = memParams + "-jar " + file + " nogui"; ProcessStartInfo processInfo = new ProcessStartInfo("java.exe", args); processInfo.CreateNoWindow = true; processInfo.UseShellExecute = false; try { using (Process minecraftProcess = Process.Start(processInfo)) { minecraftProcess.WaitForExit(); } } catch { // Log Error } } static void Main(string[] args) { Arguments CommandLine = new Arguments(args); if (CommandLine["file"] != null && CommandLine["memory"] != null) { // Launch the Application LaunchMinecraft(CommandLine["file"], CommandLine["memory"]); } else { LaunchMinecraft("minecraft_server.jar", "1024"); } } } }

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  • Writing an auto-memoizer in Scheme. Help with macro and a wrapper.

    - by kunjaan
    I am facing a couple of problems while writing an auto-memoizer in Scheme. I have a working memoizer function, which creats a hash table and checks if the value is already computed. If it has been computed before then it returns the value else it calls the function. (define (memoizer fun) (let ((a-table (make-hash))) (?(n) (define false-if-fail (?() #f)) (let ((return-val (hash-ref a-table n false-if-fail))) (if return-val return-val (begin (hash-set! a-table n (fun n)) (hash-ref a-table n))))))) Now I want to create a memoize-wrapper function like this: (define (memoize-wrapper function) (set! function (memoizer function))) And hopefully create a macro called def-memo which defines the function with the memoize-wrapper. eg. the macro could expand to (memoizer (define function-name arguments body ...) or something like that. So that I should be able to do : (def-memo (factorial n) (cond ((= n 1) 1) (else (* n (factorial (- n 1)))))) which should create a memoized version of the factorial instead of the normal slow one. My problem is that the The memoize-wrapper is not working properly, it doesnt call the memoized function but the original function. I have no idea how to write a define inside of the macro. How do I make sure that I can get variable lenght arguments and variable length body? How do I then define the function and wrap it around with the memoizer? Thanks a lot.

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  • Attempt to use a while loop for the 'next' arg of a for loop generates #arg error

    - by JerryK
    Am attempting to teach myself to program using Tcl. The task i've set myself to motivate my learning of Tcl is to solve the 8 queens problem. My approach to creating a program is to successively 'prototype' a solution. I have asked an earlier question related to the correctly laying out the nested for loops and received a helpful answer. To my dismay I find that the next development of my code creates the same interpreter error : "wrong # args" I have been careful to have an open brace at the end of the line preceding the while loop command. I've also tried to put the arguments of the whileloop in braces. This generates a different error. I have sincerely tried to understand the Tcl syntax man page - not too successfully - suggested by the answerer of my earlier question. Here is the code set allowd 1 set notallowd 0 for {set r1p 1} {$r1p <= 8} {incr r1p } { puts "1st row q placed at $r1p" ;# re-initialize r2 'free for q placemnt' array after every change of r1 q pos: for {set i 1 } {$i <= 8} {incr i} { set r2($i) $allowd } for { set r2($r1p) $notallowd ; set r2([expr $r1p-1]) $notallowd ; set r2([expr $r1p+1]) $notallowd ; set r2p 1} {$r2p <= 8} { ;# 'next' arg of r2 forloop will be a whileloop : while r2($r2p)== $notallowd incr r2p } { puts "2nd row q placed at $r2p" ;# end of 'commnd' arg of r2 forloop } } Where am I going wrong? EDIT : to provide clear reply @slebetman As stated in my text, I did brace the arguments of the whileloop (indeed that was how i first wrote the code) below is exactly the layout of the r2 forloop tried: for { set r2($r1p) $notallowd ; set r2([expr $r1p-1]) $notallowd ; set r2([expr $r1p+1]) $notallowd ; set r2p 1} {$r2p <= 8} { ;# 'next' arg of r2 forloop will be a whileloop : while { r2($r2p)== $notallowd } { incr r2p } } { puts "2nd row q placed at $r2p" ;# end of 'commnd' arg of r2 forloop } but this generates the fatal interpreter error : "unknown math function 'r2' while compiling while { r2($r2p .... "

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  • How to catch exceptions from processes in C#

    - by kitofr
    I all... I have an acceptance runner program here that looks something like this: public Result Run(CommandParser parser) { var result = new Result(); var watch = new Stopwatch(); watch.Start(); try { _testConsole.Start(); parser.ForEachInput(input => { _testConsole.StandardInput.WriteLine(input); return _testConsole.TotalProcessorTime.TotalSeconds < parser.TimeLimit; }); if (TimeLimitExceeded(parser.TimeLimit)) { watch.Stop(); _testConsole.Kill(); ReportThatTestTimedOut(result); } else { result.Status = GetProgramOutput() == parser.Expected ? ResultStatus.Passed : ResultStatus.Failed; watch.Stop(); } } catch (Exception) { result.Status = ResultStatus.Exception; } result.Elapsed = watch.Elapsed; return result; } the _testConsole is an Process adapter that wraps a regular .net process into something more workable. I do however have a hard time to catch any exceptions from the started process (i.e. the catch statement is pointless here) I'm using something like: _process = new Process { StartInfo = { FileName = pathToProcess, UseShellExecute = false, CreateNoWindow = true, RedirectStandardInput = true, RedirectStandardOutput = true, RedirectStandardError = true, Arguments = arguments } }; to set up the process. Any ideas?

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  • How to embed revision information using mercurial and maven (and svn)

    - by Zwei Steinen
    Our project had a nice hack (although I'm guessing there are better ways to do it) to embed revision information into the artifacts (jar etc.) when we used svn. Now we have migrated to mercurial, and we want to have a similar thing, but before I start working on a similar hack with mercurial, I wanted to know if there are better ways to do this. Thanks for your answers! <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>exec-maven-plugin</artifactId> <executions> <execution> <phase>process-classes</phase> <id>svninfo</id> <goals> <goal>exec</goal> </goals> <configuration> <executable>svn</executable> <arguments> <argument>info</argument> <argument>../</argument> <argument>></argument> <argument>target/some-project/META-INF/svninfo.txt</argument> </arguments> </configuration> </execution> </executions> </plugin>

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  • Why null reference exception in SetMolePublicInstance?

    - by OldGrantonian
    I get a "null reference" exception in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, null); The program builds and compiles correctly. There are no complaints about any of the parameters to the method. Here's the specification of SetMolePublicInstance, from the object browser: SetMolePublicInstance(System.Delegate _stub, System.Type receiverType, object _receiver, string name, params System.Type[] parameterTypes) Here are the parameter values for "Locals": + stub {Method = {System.String <StaticMethodUnitTestWithDeq>b__0()}} System.Func<string> + receiverType {Name = "OrigValue" FullName = "OrigValueP.OrigValue"} System.Type {System.RuntimeType} objReceiver {OrigValueP.OrigValue} object {OrigValueP.OrigValue} name "TestString" string parameterTypes null object[] I know that TestString() takes no parameters and returns string, so as a starter to try to get things working, I specified "null" for the final parameter to SetMolePublicInstance. As already mentioned, this compiles OK. Here's the stack trace: Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.ExtendedReflection.Collections.Indexable.ConvertAllToArray[TInput,TOutput](TInput[] array, Converter`2 converter) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMole(Delegate _stub, Type receiverType, Object _receiver, String name, MoleBindingFlags flags, Type[] parameterTypes) at Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(Delegate _stub, Type receiverType, Object _receiver, String name, Type[] parameterTypes) at DeqP.Deq.Replace[T](Func`1 stub, Type receiverType, Object objReceiver, String name) in C:\0VisProjects\DecP_04\DecP\DeqC.cs:line 38 at DeqPTest.DecCTest.StaticMethodUnitTestWithDeq() in C:\0VisProjects\DecP_04\DecPTest\DeqCTest.cs:line 28 at Starter.Start.Main(String[] args) in C:\0VisProjects\DecP_04\Starter\Starter.cs:line 14 Press any key to continue . . . To avoid the null parameter, I changed the final "null" to "parameterTypes" as in the following line: MoleRuntime.SetMolePublicInstance(stub, receiverType, objReceiver, name, parameterTypes); I then tried each of the following (before the line): int[] parameterTypes = null; // if this is null, I don't think the type will matter int[] parameterTypes = new int[0]; object[] parameterTypes = new object[0]; // this would allow for various parameter types All three attempts produce a red squiggly line under the entire line for SetMolePublicInstance Mouseover showed the following message: The best overloaded method match for 'Microsoft.Moles.Framework.Moles.MoleRuntime.SetMolePublicInstance(System.Delegate, System.Type, object, string, params System.Type[])' has some invalid arguments. I'm assuming that the first four arguments are OK, and that the problem is with the params array.

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  • Namespace scoped aliases for generic types in C#

    - by TN
    Let's have a following example: public class X { } public class Y { } public class Z { } public delegate IDictionary<Y, IList<Z>> Bar(IList<X> x, int i); public interface IFoo { // ... Bar Bar { get; } } public class Foo : IFoo { // ... public Bar Bar { get { return null; //... } } } void Main() { IFoo foo; //= ... IEnumerable<IList<X>> source; //= ... var results = source.Select(foo.Bar); } The compiler says: The type arguments for method 'System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly. It's because, it cannot convert Bar to Func<IList<X>, int, IDictionary<Y, IList<Z>>>. It would be great if I could create type namespace scoped type aliases for generic types in C#. Then I would define Bar not as a delegate, but rather I would define it as an namespace scoped alias for Func<IList<X>, int, IDictionary<Y, IList<Z>>>. public alias Bar = Func<IList<X>, int, IDictionary<Y, IList<Z>>>; I could then also define namespace scoped alias for e.g. IDictionary<Y, IList<Z>>. And if used appropriately:), it will make the code more readable. Now I have inline the generic types and the real code is not well readable:( Have you find the same trouble:)? Is there any good reason why it is not in C# 3.0? Or there is no good reason, it's just matter of money and/or time? EDIT: I know that I can use using, but it is not namespace based - not so convenient for my case.

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  • Adding and sorting a linked list in C

    - by user1202963
    In my assignment, I have to write a function that takes as arguments a pointer to a "LNode" structure and an integer argument. Then, I have to not only add that integer into the linked list, but also put place it so that the list is in proper ascending order. I've tried several various attempts at this, and this is my code as of posting. LNode* AddItem(LNode *headPtr, int newItem) { auto LNode *ptr = headPtr; ptr = malloc(sizeof(LNode)); if (headPtr == NULL) { ptr->value = newItem; ptr->next = headPtr; return ptr; } else { while (headPtr->value > newItem || ptr->next != NULL) { printf("While\n"); // This is simply to let me know how many times the loop runs headPtr = headPtr->next; } ptr->value = newItem; ptr->next = headPtr; return ptr; } } // end of "AddItem" When I run it, and try to insert say a 5 and then a 3, the 5 gets inserted, but then the while loop runs once and I get a segmentation fault. Also I cannot change the arguments as it's part of a skeletal code for this project. Thanks to anyone who can help. If it helps this is what the structure looks like typedef struct LNode { int value; struct LNode *next; } LNode;

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  • Which options do I have for Java process communication?

    - by Dmitriy Matveev
    We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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  • Number of characters recommended for a statement

    - by liaK
    Hi, I have been using Qt 4.5 and so do C++. I have been told that it's a standard practice to maintain the length of each statement in the application to 80 characters. Even in Qt creator we can make a right border visible so that we can know whether we are crossing the 80 characters limit. But my question is, Is it really a standard being followed? Because in my application, I use indenting and all, so it's quite common that I cross the boundary. Other cases include, there might be a error statement which will be a bit explanatory one and which is in an inner block of code, so it too will cross the boundary. Usually my variable names look bit lengthier so as to make the names meaningful. When I call the functions of the variable names, again I will cross. Function names will not be in fewer characters either. I agree a horizontal scroll bar shows up and it's quite annoying to move back and forth. So, for function calls including multiple arguments, when the boundary is reached I will make the forth coming arguments in the new line. But besides that, for a single statement (for e.g a very long error message which is in double quotes " " or like longfun1()->longfun2()->...) if I use an \ and split into multiple lines, the readability becomes very poor. So is it a good practice to have those statement length restrictions? If this restriction in statement has to be followed? I don't think it depends on a specific language anyway. I added C++ and Qt tags since if it might. Any pointers regarding this are welcome.

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  • Coldfusion 8 and HTTP PUT - is there a way to PUT an object?

    - by ciaranarcher
    Hi all We are using EHCache with CF 8 to cache stuff on a central server using a RESTful interface over HTTP. I am trying to cache a cfquery object to the cache server. I can get this to work if I call EHCache direct (i.e. store it in a local cache) but if I try to cache on a remote server over HTTP I am running into problems. The code I am using is as follows: <cfhttp url="http://localhost:8080/myCache/myKey" method="put" result="r" timeout="2" throwonerror="true" > <cfhttpparam type="body" value="#ARGUMENTS.item#" /> </cfhttp> CF doesn't like this reference to #ARGUMENTS.item# and it complains Complex object types cannot be converted to simple values. Can anyone give me an example of how to put an object over http using CF? If this is not possible with CF then a Java example would be the next best thing. Many thanks in advance! PS: I do not want to use serialization to text/JSON etc. as this approach has issues with data integrity and most importantly it's not fast enough.

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  • How to override part of an overload function in JavaScript

    - by Guan Yuxin
    I create a class with a function like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return -1; } basically it is just an overload function composed of index() and index(child). Then I create a sub class,SubObj or whatever, inherits from Obj SubObj.prototype.prototype=Obj; Now, it's time to override the index(child) function,however, index() is also in the function an I don't want to overwrite it too. One solution is to write like this var Obj=function(){this.children=[];this.parent=null;}//a base class Obj.prototype.index=function(child){ // the index of current obj if(arguments.length==0){ return this.parent?this.parent.index(this):0; } // the index of a child matchs specific obj [to be override] return this._index(this); } Obj.prototype._index=function(this){ return -1; } SubObj.prototype._index=function(this){/* overwriteing */} But this will easily mislead other coders as _index(child) should be both private(should not be used except index() function) and public(is an overload function of index(),which is public) you guys have better idea?

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  • Python class structure ... prep() method?

    - by Adam Nelson
    We have a metaclass, a class, and a child class for an alert system: class AlertMeta(type): """ Metaclass for all alerts Reads attrs and organizes AlertMessageType data """ def __new__(cls, base, name, attrs): new_class = super(AlertMeta, cls).__new__(cls, base, name, attrs) # do stuff to new_class return new_class class BaseAlert(object): """ BaseAlert objects should be instantiated in order to create new AlertItems. Alert objects have classmethods for dequeue (to batch AlertItems) and register (for associated a user to an AlertType and AlertMessageType) If the __init__ function recieves 'dequeue=True' as a kwarg, then all other arguments will be ignored and the Alert will check for messages to send """ __metaclass__ = AlertMeta def __init__(self, **kwargs): dequeue = kwargs.pop('dequeue',None) if kwargs: raise ValueError('Unexpected keyword arguments: %s' % kwargs) if dequeue: self.dequeue() else: # Do Normal init stuff def dequeue(self): """ Pop batched AlertItems """ # Dequeue from a custom queue class CustomAlert(BaseAlert): def __init__(self,**kwargs): # prepare custom init data super(BaseAlert, self).__init__(**kwargs) We would like to be able to make child classes of BaseAlert (CustomAlert) that allow us to run dequeue and to be able to run their own __init__ code. We think there are three ways to do this: Add a prep() method that returns True in the BaseAlert and is called by __init__. Child classes could define their own prep() methods. Make dequeue() a class method - however, alot of what dequeue() does requires non-class methods - so we'd have to make those class methods as well. Create a new class for dealing with the queue. Would this class extend BaseAlert? Is there a standard way of handling this type of situation?

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  • Why does exec:java work and exec:exec fail?

    - by whiskerz
    Hey there, just set up a simple project to test the functionality of the maven exec plugin. I have one class containing one "Hello World" main method. I've tested two configurations of the exec plugin. <goals> <goal>exec</goal> </goals> <configuration> <executable>java</executable> <arguments> <argument>-classpath</argument> <classpath/> <argument>test.exec.HelloWorldExec</argument> </arguments> </configuration> failed miserably, giving me a ClassNotFoundException, while <goals><goal>java</goal></goals> <configuration> <mainClass>test.exec.HelloWorldExec</mainClass> </configuration> worked. However I would like to be able to start my java main class in a separate process, so I'd like to understand whats different with exec:exec and how I can get it to work? Any help appreciated cheers Whizz

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  • in haskell, why do I need to specify type constraints, why can't the compiler figure them out?

    - by Steve
    Consider the function, add a b = a + b This works: *Main> add 1 2 3 However, if I add a type signature specifying that I want to add things of the same type: add :: a -> a -> a add a b = a + b I get an error: test.hs:3:10: Could not deduce (Num a) from the context () arising from a use of `+' at test.hs:3:10-14 Possible fix: add (Num a) to the context of the type signature for `add' In the expression: a + b In the definition of `add': add a b = a + b So GHC clearly can deduce that I need the Num type constraint, since it just told me: add :: Num a => a -> a -> a add a b = a + b Works. Why does GHC require me to add the type constraint? If I'm doing generic programming, why can't it just work for anything that knows how to use the + operator? In C++ template programming, you can do this easily: #include <string> #include <cstdio> using namespace std; template<typename T> T add(T a, T b) { return a + b; } int main() { printf("%d, %f, %s\n", add(1, 2), add(1.0, 3.4), add(string("foo"), string("bar")).c_str()); return 0; } The compiler figures out the types of the arguments to add and generates a version of the function for that type. There seems to be a fundamental difference in Haskell's approach, can you describe it, and discuss the trade-offs? It seems to me like it would be resolved if GHC simply filled in the type constraint for me, since it obviously decided it was needed. Still, why the type constraint at all? Why not just compile successfully as long as the function is only used in a valid context where the arguments are in Num? Thank you.

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  • Adding functions to Java class libraries

    - by Eric
    I'm using a Java class library that is in many ways incomplete: there are many classes that I feel ought to have additional member functions built in. However, I am unsure of the best practice of adding these member functions. Lets call the insufficient base class A. class A { public A(/*long arbitrary arguments*/) { //... } public A(/*long even more arbitrary arguments*/) { //... } public int func() { return 1; } } Ideally, I would like to add a function to A. However, I can't do that. My choice is between: class B extends A { //Implement ALL of A's constructors here public int reallyUsefulFunction() { return func()+1; } } and class AddedFuncs { public int reallyUsefulFunction(A a) { return a.func()+1; } } The way I see it, they both have advantages and disadvantages. The first choice gives a cleaner syntax than the second, and is more logical, but has problems: Let's say I have a third class, C, within the class library. class C { public A func() { return new A(/*...*/); } } As I see it, there is no easy way of doing this: C c; int useful = c.func().reallyUsefulFunction(); as the type returned by C.func() is an A, not a B, and you can't down-cast. So what is the best way of adding a member function to a read-only library class?

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  • C# Linq Select Problem in Method Chain.

    - by Gnought
    Note that the _src inherit IQueryable<U> and V inherit new(); I wrote the following statement, there is no syntax error. IQueryable<V> a = from s in _src where (s.Right - 1 == s.Left) select new V(); But if i re-wrote it as follows, the Visual Studio editor complains an error in the "Select" IQueryable<V> d = _src.Where(s => s.Right - 1 == s.Left).Select(s=> new V()); The Error is: The type arguments cannot be inferred from the usage. Try specifying the type arguments explicitly. Candidates are: System.Collections.Generic.IEnumerable<V> Select<U,V>(this System.Collections.Generic.IEnumerable<U>, System.Func<U,V>) (in class Enumerable) System.Linq.IQueryable<V> Select<U,V>(this System.Linq.IQueryable<U>, System.Linq.Expressions.Expression<System.Func<U,V>>) (in class Queryable) Could anyone explain this phenomenon, and what the solution is to fix the error?

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  • C++ Inheritance and Constructors

    - by DizzyDoo
    Hello, trying to work out how to use constructors with an inherited class. I know this is very much wrong, I've been writing C++ for about three days now, but here's my code anyway: clientData.h, two classes, ClientData extends Entity : #pragma once class Entity { public: int x, y, width, height, leftX, rightX, topY, bottomY; Entity(int x, int y, int width, int height); ~Entity(); }; class ClientData : public Entity { public: ClientData(); ~ClientData(); }; and clientData.cpp, which contains the functions: #include <iostream> #include "clientData.h" using namespace std; Entity::Entity(int x, int y, int width, int height) { this->x = x; this->y = y; this->width = width; this->height = height; this->leftX = x - (width/2); this->rightX = x + (width/2); this->topY = y - (height/2); this-bottomY = y + (height/2); } Entity::~Entity() { cout << "Destructing.\n"; } ClientData::ClientData() { cout << "Client constructed."; } ClientData::~ClientData() { cout << "Destructing.\n"; } and finally, I'm creating a new ClientData with: ClientData * Data = new ClientData(32,32,32,16); Now, I'm not surprised my compiler shouts errors at me, so how do I pass the arguments to the right classes? The first error (from MVC2008) is error C2661: 'ClientData::ClientData' : no overloaded function takes 4 arguments and the second, which pops up whatever changes I seem to make is error C2512: 'Entity' : no appropriate default constructor available Thanks.

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  • Drupal 7 - I can't pass post data in module function

    - by user2603290
    I can't pass post data in my custom module. filenames: mymodule.info mymodule.mod .info name = My Module description = My custom module. package = DEV version = 1.0 core = 7.x .module <?php function mymodule_menu() { $items = array(); $items['getcountries'] = array( 'title' => 'Get Countries', 'page callback' => 'getcountries', 'access arguments' => array('access content'), 'type' => MENU_CALLBACK, ); $items['getstates'] = array( 'title' => 'Get States', 'page callback' => 'getstates', 'access arguments' => array('access content'), 'type' => MENU_CALLBACK, ); return $items; } function getcountries() { $result = db_query("select distinct(country) from region"); $jsonarray = Array(); foreach ($result as $record) { $jsonarray[] = array( 'item' => $record->country, 'value' => $record->country ); } $json = json_encode($jsonarray); echo $json; } function getstates() { echo $_POST["test"]; } Ajax call $(document).ready(function(){ $.ajax({ url: '/getstates', type: 'POST', data: '{"test":"1"}', success : function () { alert('ok'); }, error : function (jqXHR, textStatus, errorThrown) { alert('error'); } }); }); The first item "getcountries" is working fine however the second one is not. I can browse to http://mysite.com/getstates ok but when I call this function using ajax it is not passing the value of "test" which is "1" to $_POST["test"]. I am new to Drupal so I am positive that I miss something here. I thought I need a new set of eyes.

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  • Allowing connections initiated from outside

    - by Mark S. Rasmussen
    I've got an old Juniper SSG5 running ScreenOS 5.4.0r6.0. Once a day, more or less, it'll start randomly dropping packets at a rate of ~5-10%. We currently solve this issue by simply rebooting the unit, after which it resumes working in perfect condition. As this error has started appearing randomly, without any configuration or hardware changes, I'm assuming I've got an aging unit about to fail. As such, I've got a replacement SSG5 running ScreenOS 6.0. I've dumped the config on the 5.4 and imported it into a clean 6.0, and it seems to gladly accept it, and all my configuration seems to be A-OK. However, upon connecting the new unit, all outside-initiated connections seem to be blocked. If I browse our external IP from the inside, everything works perfectly, and it's not just port 80, SSH, Crashplan - all of our policies route correctly. All normal networking, initiated from the inside, work perfectly as well. If on the other hand I browse our external IP from the outside, everything is blocked. Barring differences between ScreenOS 5.4 and 6.0, the config is identical. Is there a setting somewhere that defines whether outside/inside initiated connections are allowed? unset key protection enable set clock timezone 1 set vrouter trust-vr sharable set vrouter "untrust-vr" exit set vrouter "trust-vr" unset auto-route-export exit set service "MyVOIP_UDP4569" protocol udp src-port 0-65535 dst-port 4569-4569 set service "MyVOIP_TCP22" protocol tcp src-port 0-65535 dst-port 22-22 set service "MyRDP" protocol tcp src-port 0-65535 dst-port 3389-3389 set service "MyRsync" protocol tcp src-port 0-65535 dst-port 873-873 set service "NZ_FTP" protocol tcp src-port 0-65535 dst-port 40000-41000 set service "NZ_FTP" + tcp src-port 0-65535 dst-port 21-21 set service "PPTP-VPN" protocol 47 src-port 2048-2048 dst-port 2048-2048 set service "PPTP-VPN" + tcp src-port 1024-65535 dst-port 1723-1723 set service "NZ_FMS_1935" protocol tcp src-port 0-65535 dst-port 1935-1935 set service "NZ_FMS_1935" + udp src-port 0-65535 dst-port 1935-1935 set service "NZ_FMS_8080" protocol tcp src-port 0-65535 dst-port 8080-8080 set service "CrashPlan Server" protocol tcp src-port 0-65535 dst-port 4280-4280 set service "CrashPlan Console" protocol tcp src-port 0-65535 dst-port 4282-4282 unset alg sip enable set alg appleichat enable unset alg appleichat re-assembly enable set alg sctp enable set auth-server "Local" id 0 set auth-server "Local" server-name "Local" set auth default auth server "Local" set auth radius accounting port 1646 set admin name "netscreen" set admin password "XXX" set admin auth web timeout 10 set admin auth dial-in timeout 3 set admin auth server "Local" set admin format dos set vip multi-port set zone "Trust" vrouter "trust-vr" set zone "Untrust" vrouter "trust-vr" set zone "DMZ" vrouter "trust-vr" set zone "VLAN" vrouter "trust-vr" set zone "Untrust-Tun" vrouter "trust-vr" set zone "Trust" tcp-rst set zone "Untrust" block unset zone "Untrust" tcp-rst set zone "MGT" block unset zone "V1-Trust" tcp-rst unset zone "V1-Untrust" tcp-rst set zone "DMZ" tcp-rst unset zone "V1-DMZ" tcp-rst unset zone "VLAN" tcp-rst set zone "Untrust" screen tear-drop set zone "Untrust" screen syn-flood set zone "Untrust" screen ping-death set zone "Untrust" screen ip-filter-src set zone "Untrust" screen land set zone "V1-Untrust" screen tear-drop set zone "V1-Untrust" screen syn-flood set zone "V1-Untrust" screen ping-death set zone "V1-Untrust" screen ip-filter-src set zone "V1-Untrust" screen land set interface ethernet0/0 phy full 100mb set interface ethernet0/3 phy full 100mb set interface ethernet0/4 phy full 100mb set interface ethernet0/5 phy full 100mb set interface ethernet0/6 phy full 100mb set interface "ethernet0/0" zone "Untrust" set interface "ethernet0/1" zone "Null" set interface "bgroup0" zone "Trust" set interface "bgroup1" zone "Trust" set interface "bgroup2" zone "Trust" set interface bgroup2 port ethernet0/2 set interface bgroup0 port ethernet0/3 set interface bgroup0 port ethernet0/4 set interface bgroup1 port ethernet0/5 set interface bgroup1 port ethernet0/6 unset interface vlan1 ip set interface ethernet0/0 ip 215.173.182.18/29 set interface ethernet0/0 route set interface bgroup0 ip 192.168.1.1/24 set interface bgroup0 nat set interface bgroup1 ip 192.168.2.1/24 set interface bgroup1 nat set interface bgroup2 ip 192.168.3.1/24 set interface bgroup2 nat set interface ethernet0/0 gateway 215.173.182.17 unset interface vlan1 bypass-others-ipsec unset interface vlan1 bypass-non-ip set interface ethernet0/0 ip manageable set interface bgroup0 ip manageable set interface bgroup1 ip manageable set interface bgroup2 ip manageable set interface bgroup0 manage mtrace unset interface bgroup1 manage ssh unset interface bgroup1 manage telnet unset interface bgroup1 manage snmp unset interface bgroup1 manage ssl unset interface bgroup1 manage web unset interface bgroup2 manage ssh unset interface bgroup2 manage telnet unset interface bgroup2 manage snmp unset interface bgroup2 manage ssl unset interface bgroup2 manage web set interface ethernet0/0 vip 215.173.182.19 2048 "PPTP-VPN" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.19 + 4280 "CrashPlan Server" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.19 + 4282 "CrashPlan Console" 192.168.1.131 set interface ethernet0/0 vip 215.173.182.22 22 "MyVOIP_TCP22" 192.168.2.127 set interface ethernet0/0 vip 215.173.182.22 + 4569 "MyVOIP_UDP4569" 192.168.2.127 set interface ethernet0/0 vip 215.173.182.22 + 3389 "MyRDP" 192.168.2.202 set interface ethernet0/0 vip 215.173.182.22 + 873 "MyRsync" 192.168.2.201 set interface ethernet0/0 vip 215.173.182.22 + 80 "HTTP" 192.168.2.202 set interface ethernet0/0 vip 215.173.182.22 + 2048 "PPTP-VPN" 192.168.2.201 set interface ethernet0/0 vip 215.173.182.22 + 8080 "NZ_FMS_8080" 192.168.2.216 set interface ethernet0/0 vip 215.173.182.22 + 1935 "NZ_FMS_1935" 192.168.2.216 set interface bgroup0 dhcp server service set interface bgroup1 dhcp server service set interface bgroup2 dhcp server service set interface bgroup0 dhcp server auto set interface bgroup1 dhcp server auto set interface bgroup2 dhcp server auto set interface bgroup0 dhcp server option domainname companyalan set interface bgroup0 dhcp server option dns1 192.168.1.131 set interface bgroup1 dhcp server option domainname companyblan set interface bgroup1 dhcp server option dns1 192.168.2.202 set interface bgroup2 dhcp server option dns1 8.8.8.8 set interface bgroup2 dhcp server option wins1 8.8.4.4 set interface bgroup0 dhcp server ip 192.168.1.2 to 192.168.1.116 set interface bgroup1 dhcp server ip 192.168.2.2 to 192.168.2.116 set interface bgroup2 dhcp server ip 192.168.3.2 to 192.168.3.126 unset interface bgroup0 dhcp server config next-server-ip unset interface bgroup1 dhcp server config next-server-ip unset interface bgroup2 dhcp server config next-server-ip set interface "ethernet0/0" mip 215.173.182.21 host 192.168.2.202 netmask 255.255.255.255 vr "trust-vr" set interface "serial0/0" modem settings "USR" init "AT&F" set interface "serial0/0" modem settings "USR" active set interface "serial0/0" modem speed 115200 set interface "serial0/0" modem retry 3 set interface "serial0/0" modem interval 10 set interface "serial0/0" modem idle-time 10 set flow tcp-mss unset flow tcp-syn-check unset flow tcp-syn-bit-check set flow reverse-route clear-text prefer set flow reverse-route tunnel always set pki authority default scep mode "auto" set pki x509 default cert-path partial set pki x509 dn name "[email protected]" set dns host dns1 0.0.0.0 set dns host dns2 0.0.0.0 set dns host dns3 0.0.0.0 set address "Trust" "192.168.1.0/24" 192.168.1.0 255.255.255.0 set address "Trust" "192.168.2.0/24" 192.168.2.0 255.255.255.0 set address "Trust" "192.168.3.0/24" 192.168.3.0 255.255.255.0 set crypto-policy exit set ike respond-bad-spi 1 set ike ikev2 ike-sa-soft-lifetime 60 unset ike ikeid-enumeration unset ike dos-protection unset ipsec access-session enable set ipsec access-session maximum 5000 set ipsec access-session upper-threshold 0 set ipsec access-session lower-threshold 0 set ipsec access-session dead-p2-sa-timeout 0 unset ipsec access-session log-error unset ipsec access-session info-exch-connected unset ipsec access-session use-error-log set vrouter "untrust-vr" exit set vrouter "trust-vr" exit set l2tp default ppp-auth chap set url protocol websense exit set policy id 1 from "Trust" to "Untrust" "Any" "Any" "ANY" permit set policy id 1 exit set policy id 2 from "Untrust" to "Trust" "Any" "VIP(215.173.182.19)" "PPTP-VPN" permit traffic set policy id 2 exit set policy id 3 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "HTTP" permit log set policy id 3 set service "MyRDP" set service "MyRsync" set service "MyVOIP_TCP22" set service "MyVOIP_UDP4569" exit set policy id 6 from "Trust" to "Trust" "192.168.1.0/24" "192.168.2.0/24" "ANY" deny set policy id 6 exit set policy id 7 from "Trust" to "Trust" "192.168.2.0/24" "192.168.1.0/24" "ANY" deny set policy id 7 exit set policy id 8 from "Trust" to "Trust" "192.168.3.0/24" "192.168.1.0/24" "ANY" deny set policy id 8 exit set policy id 9 from "Trust" to "Trust" "192.168.3.0/24" "192.168.2.0/24" "ANY" deny set policy id 9 exit set policy id 10 from "Untrust" to "Trust" "Any" "MIP(215.173.182.21)" "NZ_FTP" permit set policy id 10 exit set policy id 11 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "PPTP-VPN" permit set policy id 11 exit set policy id 12 from "Untrust" to "Trust" "Any" "VIP(215.173.182.22)" "NZ_FMS_1935" permit set policy id 12 set service "NZ_FMS_8080" exit set policy id 13 from "Untrust" to "Trust" "Any" "VIP(215.173.182.19)" "CrashPlan Console" permit set policy id 13 set service "CrashPlan Server" exit set nsmgmt bulkcli reboot-timeout 60 set ssh version v2 set config lock timeout 5 unset license-key auto-update set telnet client enable set snmp port listen 161 set snmp port trap 162 set vrouter "untrust-vr" exit set vrouter "trust-vr" unset add-default-route exit set vrouter "untrust-vr" exit set vrouter "trust-vr" exit Note that I've previously posted a similar question (pertaining to the same device & replacement, but ultimately caused by a malfunctioning switch, and thus clouding the current issue): Outbound traffic being blocked for MIP/VIPped servers (Juniper SSG5)

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