In Scala 2.7, I could write:
package com.acme.bar
class Bar
.
package com.acme.foo
class Foo {
new bar.Bar
}
This doesn't compile in Scala 2.8 -- however this does:
package com.acme
package bar
class Bar
.
package com.acme
package foo
class Foo {
new bar.Bar
}
What was the motivation for this?
What is the precise meaning, with regards to scope and visibility?
When should I use one form over the other?
Let's assume that I have files a.cpp b.cpp and file c.h. Both of the cpp files include the c.h file. The header file contains a bunch of const int definitions and when I compile them I get no errors and yet I can access those const as if they were global variables. So the question, why don't I get any compilation errors if I have multiple const definitions as well as these const int's having global-like scope?
What i did:
create a project,
edited the ui file with the designer tool,
ran the project, everything is ok
tried to add to my cppfile:
connect( pushButton_bracketBegin, SIGNAL( clicked() ), this, SLOT( pushButton_bracketBeginAction() ) );
but i get the error "‘pushButton_bracketBegin’ was not declared in this scope". this is my first project in qt and it should be fairly simple i guess (but yet out of my grasp ) :) appreciate the help
I always thought that varibales are mapped to stack locations once your Java source is compiled; additionally, they may include the info about the variable names and their scope in classfiles, but that's optional AFAIK.
The question is - how do my Eclipse/IDEA IDEs allow me to set a watch expression containing the local variable name? To me, it's hard to understand :)
When building gtk2hs-buildtools with ghc 7.4.2, I get the following warning:
c2hs/toplevel/C2HSConfig.hs:110:1:
Warning: newtype `CInt' is used in an FFI declaration,
but its constructor is not in scope.
This will become an error in GHC 7.6.1.
When checking declaration:
foreign import ccall safe "static bitfield_direction" bitfield_direction
:: CInt
I get similar warnings with FFI calls, even though I have import Foreign.C.Types(CInt).
What is the correct way of getting rid of this warning?
Hi,
I just downloaded SpringSource Tool Suite, and tried to generate a demo application using roo, but i'm getting error below
Code:
Created /home/dev/springsource/workspace/demo/pom.xml
Undo create /home/dev/springsource/workspace/demo/pom.xml
Invalid dependency scope: PROVIDED
[Timer-0] NullPointerException at org.springframework.roo.classpath.itd.AbstractItdMetadataProvider.notify(AbstractItdMetadataProvider.java:84)
What is the problem? is this Maven issue?
Using: Ubuntu 8.10, SpringSource Tool Suite Version: 2.3.3.M1, Roo 1.1.0.M1, Apache Maven
Thanks
What is the memory and performance usage compared to creating a object with only a constructor?
The usage here is in creating a Set<Object> or List<Object> that may contain million plus entries and I am concerned with the overhead of using Bloch's Builder Pattern. I have used it in the past, but never in this large of a scope.
If my class has NO destructor, an it goes out of scope.
GC runs at certain time, now will it simply reclaim memory from my class OR will it call its destructor or Finalize () on it ?
And does the .net framework class like SQLConnection implement a destructor? I saw it has a Dispose () implementation but didn't see the destructor using "Go to definition".
After completing a XHTML , CSS project , and Even client is happy, should I try to optimize my HTML, CSS code if there is any scope?
If yes then how to more improve and optimize code and what things can/should be optimized?
Should i optimize to get lowest file size or i should optimize code for better readability?
I noticed that doxygen uses the graphviz library for creating diagrams. Have you ever used graphviz for generating documentation? Is it worth learning the graphviz for documentation purposes outside the scope of doxygen? Or am I better off to sticking with a standard data modeling package like Visio?
I understand the merits of it as a graphing library, but for trying to represent more complex UML (or similar) is it still worth looking into?
Everything seems to work fine until i want to submit the form and update the database.
Wildcard mapping works on requests like "/navigation/edit/1", but when i submit the form as:
var ajaxPost = function(Url, Params) {
Ext.Ajax.request({
url: Url,
params: Params,
method: 'POST',
async: false,
scope: this
});
};
it says "200 bad response: syntax error" and in firebug there is "Failed to load source for: http://.../Navigation/edit/1".
Any help?
This may seem a trivial question, but it's one that's bothered me a lot lately. Why do some programmers refer to "C++/STL" like it's a different language? The STL is part of the C++ standard library -- and therefore is part of the language, "C++". It's not a separate component, and it does not live alone in the scope of things C++. Yet some continually act like it's a different language altogether. Why?
This shows how to have a static variable inside an object or context:
http://www.mail-archive.com/[email protected]/msg04764.html
But the scope is too large for some needs, is it possible to have a static variable inside an object function ?
i always using the following format to use transactionscope.
using(TransactionScope scope = new TransactionScope()){
....
}
sometimes i want to wrap the transactionscope to a new class, for example DbContext class, i want to using the statement like
dbContext.Begin();
...
dbContext.Submit();
it seems the transactioncope class need use "using"statement to do dispose, i want to know if there is anyway not use "using".
Hi all;
var v_name = null;
$.ajax({
type: "GET",
url: "Testpage.aspx",
data: "name=test",
dataType: "html",
success: function(mydata) {
v_name= mydata;
}
});
alert(v_name);
Output: alert in null
"success" scope in alert work
how to make ? pls help
If I use objc_setAssociatedObject/objc_getAssociatedObject inside a category implementation to store a simulated instance variable in a setter method, how would I access the key in the getter method since any variables declared in the setter method would be outside the scope of the getter method?
After some resent tests I have found my implementation cannot handle very much recursion. Although after I ran a few tests in Firefox I found that this may be more common than I originally thought. I believe the basic problem is that my implementation requires 3 calls to make a function call. The first call is made to a method named Call that makes sure the call is being made to a callable object and gets the value of any arguments that are references. The second call is made to a method named Call which is defined in the ICallable interface. This method creates the new execution context and builds the lambda expression if it has not been created. The final call is made to the lambda that the function object encapsulates. Clearly making a function call is quite heavy but I am sure that with a little bit of tweaking I can make recursion a viable tool when using this implementation.
public static object Call(ExecutionContext context, object value, object[] args)
{
var func = Reference.GetValue(value) as ICallable;
if (func == null)
{
throw new TypeException();
}
if (args != null && args.Length > 0)
{
for (int i = 0; i < args.Length; i++)
{
args[i] = Reference.GetValue(args[i]);
}
}
var reference = value as Reference;
if (reference != null)
{
if (reference.IsProperty)
{
return func.Call(reference.Value, args);
}
else
{
return func.Call(((EnviromentRecord)reference.Value).ImplicitThisValue(), args);
}
}
return func.Call(Undefined.Value, args);
}
public object Call(object thisObject, object[] arguments)
{
var lexicalEnviroment = Scope.NewDeclarativeEnviroment();
var variableEnviroment = Scope.NewDeclarativeEnviroment();
var thisBinding = thisObject ?? Engine.GlobalEnviroment.GlobalObject;
var newContext = new ExecutionContext(Engine, lexicalEnviroment, variableEnviroment, thisBinding);
Engine.EnterContext(newContext);
var result = Function.Value(newContext, arguments);
Engine.LeaveContext();
return result;
}
Consider the code:
On Error Goto ErrorHandler
Using sr As StreamReader = New StreamReader(OpenFile)
str = sr.ReadToEnd
sr.Close()
End Using
Exit Sub
ErrorHandler:
If there is an error inside the Using block how do you clean up the sr object?
The sr object is not in scope in ErrHandler so sr.Close() cannot be called. Does the Using block cleanup any resources automatically even if there is an error?
Maybe I should back-up and widen the scope before diving into the title question...
I'm currently writing a web app in ASP.NET MVC 1.0 (although I do have MVC 2.0 installed on my PC, so I'm not exactly restricted to 1.0) -- I've started with the standard MVC project which has your basic "Welcome to ASP.NET MVC" and shows both the [Home] tab and [About] tab in the upper-right corner. Pretty standard, right?
I've added 4 new Controller classes, let's call them "Astronomer", "Biologist", "Chemist", and "Physicist". Attached to each new controller class is the [Authorize] attribute.
For example, for the BiologistController.cs
[Authorize(Roles = "Biologist,Admin")]
public class BiologistController : Controller
{
public ActionResult Index() { return View(); }
}
These [Authorize] tags naturally limit which user can access different controllers depending on Roles, but I want to dynamically build a Menu at the top of my website in the Site.Master Page based on the Roles the user is a part of. So for example, if JoeUser was a member of Roles "Astronomer" and "Physicist", the navigation menu would say:
[Home] [Astronomer] [Physicist]
[About]
And naturally, it would not list links to "Biologist" or "Chemist" controller Index page.
Or if "JohnAdmin" was a member of Role "Admin", links to all 4 controllers would show up in the navigation bar.
Ok, you prolly get the idea...
Starting with the answer from this StackOverflow topic about Dynamic Menu building in ASP.NET, I'm trying to understand how I would fully implement this. (I'm a newbie and need a little more guidance, so please bare with me.)
The answer proposes Extending the Controller class (call it "ExtController") and then have each new WhateverController inherit from ExtController.
My conclusion is that I would need to use Reflection in this ExtController Constructor to determine which Classes and Methods have [Authorize] attributes attached to them to determine the Roles. Then using a Static Dictionary, store the Roles and Controllers/Methods in key-value pairs.
I imagine it something like this:
public class ExtController : Controller
{
protected static Dictionary<Type,List<string>> ControllerRolesDictionary;
protected override void OnActionExecuted(ActionExecutedContext filterContext)
{
// build list of menu items based on user's permissions, and add it to ViewData
IEnumerable<MenuItem> menu = BuildMenu();
ViewData["Menu"] = menu;
}
private IEnumerable<MenuItem> BuildMenu()
{
// Code to build a menu
SomeRoleProvider rp = new SomeRoleProvider();
foreach (var role in rp.GetRolesForUser(HttpContext.User.Identity.Name))
{
}
}
public ExtController()
{
// Use this.GetType() to determine if this Controller is already in the Dictionary
if (!ControllerRolesDictionary.ContainsKey(this.GetType()))
{
// If not, use Reflection to add List of Roles to Dictionary
// associating with Controller
}
}
}
Is this doable? If so, how do I perform Reflection in the ExtController constructor to discover the [Authorize] attribute and related Roles (if any)
ALSO! Feel free to go out-of-scope on this question and suggest an alternate way of solving this "Dynamic Site.Master Menu based on Roles" problem. I'm the first to admit that this may not be the best approach.
My session objects are only stored within the request scope on google app engine and I can't figure out how to persist objects between requests. The docs are next to useless on this matter and I can't find anyone who's experienced a similar problem. Please help.
When I store session objects in the servlet and forward the request to a JSP using:
getServletContext().getRequestDispatcher("/example.jsp").forward(request,response);
Everything works like it should. But when I store objects to the session and redirect the request using:
response.sendRedirect("/example/url");
The session objects are lost to the ether. In fact when I dump session key/value pairs on new requests there is absolutely nothing, session objects only appear within the request scope of servlets which create session objects. It appears to me that the objects are not being written to Memcache or Datastore.
In terms of configuring sessions for my application I have set
<sessions-enabled>true</sessions-enabled>
In appengine-web.xml. Is there anything else I am missing?
The single paragraph of documentation on sessions also notes that only objects which implement Serializable can be stored in the session between requests. I have included an example of the code which is not working below.
The obvious solution is to not use redirects, and this might be ok for the example given below but some application data does need to be stored in the session between requests so I need to find a solution to this problem.
EXAMPLE: The class FlashMessage gives feedback to the user from server-side operations.
if (email.send()) {
FlashMessage flash = new FlashMessage(FlashMessage.SUCCESS, "Your message has been sent.");
session.setAttribute(FlashMessage.SESSION_KEY, flash);
// The flash message will not be available in the session object in the next request
response.sendRedirect(URL.HOME);
} else {
FlashMessage flash = new FlashMessage(FlashMessage.ERROR, FlashMessage.INVALID_FORM_DATA);
session.setAttribute(FlashMessage.SESSION_KEY, flash);
// The flash message is displayed without problem
getServletContext().getRequestDispatcher(Templates.CONTACT_FORM).forward(request,response);
}
FlashMessage.java
import java.io.Serializable;
public class FlashMessage implements Serializable {
private static final long serialVersionUID = 8109520737272565760L; // I have tried using different, default and no serialVersionUID
public static final String SESSION_KEY = "flashMessage";
public static final String ERROR = "error";
public static final String SUCCESS = "success";
public static final String INVALID_FORM_DATA = "Your request failed to validate.";
private String message;
private String type;
public FlashMessage (String type, String message) {
this.type = type;
this.message = message;
}
public String display(){
return "<div id='flash' class='" + type + "'>" + message + "</div>";
}
}
I want to return StudentId to use elsewhere outside of the scope of the $.getJSON()
j.getJSON(url, data, function(result)
{
var studentId = result.Something;
});
//use studentId here
I would imagine this has to do with scoping, but it doesn't seem to work the same way c# does
I was used to use RockScroll (or MetalScroll), but when I started to use ReSharper my RockScroll start to show some bugs. Well, this is scope to another discussion http://stackoverflow.com/questions/1089493/is-rockscroll-compatible-with-resharper.
But my problem is related, because now without MetalScroll I can't highlight all occurrences, what I consider very useful in many situations.
Someone have another plugin for VS2010 or for ReSharper that do the same or better?
In Scala 2.7, I could write:
package com.acme.bar
class Bar
.
package com.acme.foo
class Foo {
new bar.Bar
}
This doesn't compile in Scala 2.8 -- however this does:
package com.acme
package bar
class Bar
.
package com.acme
package foo
class Foo {
new bar.Bar
}
What was the motivation for this?
What is the precise meaning, with regards to scope and visibility?
When should I use one form over the other?