How to use Code Contracts with query? - linq

I am fairly new to Code Contracts...and I ran into a problem.
I have in a method LINQ query that go something like this:
MyClass[] fields =
(from p in rType.GetProperties()
where p.CanRead
let fAttr = p.GetCustomAttributes(typeof(MyClassAttribute), true).SingleOrDefault() as MyClassAttribute
where fAttr != null
select new MyClass(p, fAttr)).ToArray();
And I want to implement Code Contracts in my project. I have done everything OK, until I got to this point. When I run static checker, it suggest to me that I need to add a couple of preconditions (Contract.Requires) regarding variables p and fAttr which are defined in the query. And also, I have a couple of unproven requires.
How can I solve this? Any ideas?
MyClass also contains two preconditions:
internal MyClass(PropertyInfo p, MyClassAttribute att)
{
Contract.Requires(p != null);
Contract.Requires(att != null);
...
}
Thanks in advance :)

I can't seem to reproduce this. Are you using the latest version of Code Contracts?
My entire code looks like this... is this close enough to your version?
using System;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Reflection;
namespace ConsoleApplication10
{
class Program
{
class MyClassAttribute : Attribute{}
class MyClass
{
internal MyClass(PropertyInfo p, MyClassAttribute a)
{
Contract.Requires(p != null);
Contract.Requires(a != null);
}
}
static void Main(string[] args)
{
var rType = typeof (DateTime);
MyClass[] result = (from p in rType.GetProperties()
where p.CanRead
let fAttr = p.GetCustomAttributes(typeof(MyClassAttribute), true).SingleOrDefault() as MyClassAttribute
where fAttr != null
select new MyClass(p, fAttr)).ToArray();
}
}
}

Related

V3125 False Positive

PVS Studio throws V3125: The 'control.Parent' object was used after it was verified against null. Check lines: 11, 9.
using System.Windows.Forms;
namespace V3125_False_Positive
{
static class Program
{
static void Main()
{
if (new Control() is Control control && control.Parent != null)
{
string parentname = control.Parent.Name;
}
}
}
}
Is this a false positive?
Indeed, this is a false positive. We'll look into it and try fixing it for the next release (actually, for the release after the next one, as we are planning to release a new version in about a week, so the fix will not make it).
Thanks for the tip!

Cannot convert lambda expression to type 'string' because it is not a delegate type

w => w.ClassName == "Button" && new WinButton(w.Hwnd).Title == "OK"
I am using a class that clicks 'OK' on the all dialog windows that opens while testing a website on Watin. But this line gives an error of lambda expression cannot be converted to type string because it is not a delegate type.
I have used using System.Linq and still does not work
Please help me out!
The whole code is as follows:
using System;
using System.Text;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using WatiN.Core;
using SCO.Automated.Testing.Service;
using WatiN.Core.DialogHandlers;
using WatiN.Core.Native.Windows;
using WatiN.Core.Native.InternetExplorer;
namespace SCO.Automated.Testing.Service
{
public class OKDialogHandler : BaseDialogHandler
{
public override bool HandleDialog(Window window)
{
var button = GetOKButton(window);
if (button != null)
{
button.Click();
return true;
}
else
{
return false;
}
}
public override bool CanHandleDialog(Window window)
{
return GetOKButton(window) != null;
}
private WinButton GetOKButton(Window window)
{
var windowButton = new WindowsEnumerator().GetChildWindows(window.Hwnd, w => w.ClassName == "Button" && new WinButton(w.Hwnd).Title == "OK").FirstOrDefault();
if (windowButton == null)
return null;
else
return new WinButton(windowButton.Hwnd);
}
}
}
Given the code here, that looks fine to me.
Is it possible that you're using an older version of WatiN which doesn't have that overload? If you look in WindowsEnumerator in Reflector, do you see this overload?
public IList<Window> GetChildWindows(IntPtr hwnd,
WindowEnumConstraint constraint)

How to invoke async operation as sync?

I have a third party service which have async DoAsync() operation and Done() event. How can I create my own sync DoSync() operation?
I want smth like this (in pseudocode):
operation DoSync()
{
DoAsync();
wait until Done();
}
Try the AutoResetEvent http://msdn.microsoft.com/en-us/library/system.threading.autoresetevent.aspx
One way to do this is to temporarily add an event handler, and in that handler, set some sort of waitable object. Here's an example that shows the technique with one of the async methods provided by WebClient
using System;
using System.Net;
using System.Threading;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
WebClient w = new WebClient();
using (var waiter = new ManualResetEventSlim())
{
DownloadDataCompletedEventHandler h = (sender, e) =>
{
if (e.Error != null)
{
Console.WriteLine(e.Error);
}
waiter.Set();
};
w.DownloadDataCompleted += h;
try
{
w.DownloadDataAsync(new Uri("http://www.interact-sw.co.uk/iangblog/"));
Console.WriteLine("Downloading");
waiter.Wait();
Console.WriteLine("Finished!");
}
finally
{
w.DownloadDataCompleted -= h;
}
}
}
}
}
Here's a simplified version that makes the basic technique easier to see, but which doesn't bother with things like error handling, or tidying up after itself:
WebClient w = new WebClient();
using (var waiter = new ManualResetEventSlim())
{
w.DownloadDataCompleted += delegate { waiter.Set(); };
w.DownloadDataAsync(new Uri("http://www.interact-sw.co.uk/iangblog/"));
Console.WriteLine("Downloading");
waiter.Wait();
Console.WriteLine("Finished!");
}
In most situations you will want to make sure you detect errors, and detach the handler when you're done - I just provided the shorter version to help illustrate the point. I wouldn't actually use that simplified one in a real program.

How to read the contents of a screen from another application [Office Communicator]

Knowing the hwnd of the window, how do I read the contents of this? Before anyone ask me, I'm trying to get the text that was used in the Communicator window.
Below is the code I found on the Internet.
The code is not mine.
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace EventFun
{
class EventHookUp
{
CommunicatorAPI.Messenger mCommunicator = null;
static void Main(string[] args)
{
EventHookUp hu = new EventHookUp();
hu.InitializeEventHocks();
Console.ReadKey();
}
public void InitializeEventHocks()
{
mCommunicator = new CommunicatorAPI.Messenger();
mCommunicator.OnIMWindowCreated += new CommunicatorAPI.DMessengerEvents_OnIMWindowCreatedEventHandler(mCommunicator_OnIMWindowCreated);
mCommunicator.OnIMWindowDestroyed += new CommunicatorAPI.DMessengerEvents_OnIMWindowDestroyedEventHandler(mCommunicator_OnIMWindowDestroyed);
}
void mCommunicator_OnIMWindowCreated(object pIMWindow)
{
CommunicatorAPI.IMessengerConversationWndAdvanced stpIMWindow = pIMWindow as CommunicatorAPI.IMessengerConversationWndAdvanced;
//stpIMWindow.History;
long Hwnd = (long)stpIMWindow.HWND;
Console.WriteLine("New IM Window Created : {0}", Hwnd);
CommunicatorAPI.IMessengerContacts contactList = (CommunicatorAPI.IMessengerContacts)stpIMWindow.Contacts;
StringBuilder sb = new StringBuilder();
foreach (CommunicatorAPI.IMessengerContact imc in contactList)
{
sb.Append(imc.FriendlyName);
sb.Append(Environment.NewLine);
}
Console.WriteLine(sb.ToString());
}
void mCommunicator_OnIMWindowDestroyed(object pIMWindow)
{
Console.WriteLine("IM Window Destroyed.");
}
}
}
It sounds like you are trying to get the conversation text history from the conversation window? If so, George Durzi has an excellent blog post on this.
As this blog post is not available, I used below method to retrieve the conversation history:
object obj = msgrAdv.StartConversation(
CONVERSATION_TYPE.CONVERSATION_TYPE_IM, // Type of conversation
sipUris, // object array of signin names for having multiple conversations or just a string
null,
"Test",
"1",
null);
imWindowHandle = long.Parse(obj.ToString());
if (imWindow == null) //If there is already an open window...
{
imWindow = (IMessengerConversationWndAdvanced)msgrAdv.InstantMessage(sipUris);
}
//else there was no open window, we have opened the window using "msgrAdv.StartConversation" so there is a imWindow associated which is implemented in communicator_OnIMWindowCreated.
//and then...
string history = imWindow.History;

How to tell if .NET code is being run by Visual Studio designer

I am getting some errors thrown in my code when I open a Windows Forms form in Visual Studio's designer. I would like to branch in my code and perform a different initialization if the form is being opened by designer than if it is being run for real.
How can I determine at run-time if the code is being executed as part of designer opening the form?
if (System.ComponentModel.LicenseManager.UsageMode == System.ComponentModel.LicenseUsageMode.Designtime)
{
// Design time logic
}
To find out if you're in "design mode":
Windows Forms components (and controls) have a DesignMode property.
Windows Presentation Foundation controls should use the IsInDesignMode attached property.
The Control.DesignMode property is probably what you're looking for. It tells you if the control's parent is open in the designer.
In most cases it works great, but there are instances where it doesn't work as expected. First, it doesn't work in the controls constructor. Second, DesignMode is false for "grandchild" controls. For example, DesignMode on controls hosted in a UserControl will return false when the UserControl is hosted in a parent.
There is a pretty easy workaround. It goes something like this:
public bool HostedDesignMode
{
get
{
Control parent = Parent;
while (parent!=null)
{
if(parent.DesignMode) return true;
parent = parent.Parent;
}
return DesignMode;
}
}
I haven't tested that code, but it should work.
The most reliable approach is:
public bool isInDesignMode
{
get
{
System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess();
bool res = process.ProcessName == "devenv";
process.Dispose();
return res;
}
}
The most reliable way to do this is to ignore the DesignMode property and use your own flag that gets set on application startup.
Class:
public static class Foo
{
public static bool IsApplicationRunning { get; set; }
}
Program.cs:
[STAThread]
static void Main()
{
Foo.IsApplicationRunning = true;
// ... code goes here ...
}
Then just check the flag whever you need it.
if(Foo.IsApplicationRunning)
{
// Do runtime stuff
}
else
{
// Do design time stuff
}
I had the same problem in Visual Studio Express 2013. I tried many of the solutions suggested here but the one that worked for me was an answer to a different thread, which I will repeat here in case the link is ever broken:
protected static bool IsInDesigner
{
get { return (Assembly.GetEntryAssembly() == null); }
}
The devenv approach stopped working in VS2012 as the designer now has its own process. Here is the solution I am currently using (the 'devenv' part is left there for legacy, but without VS2010 I am not able to test that though).
private static readonly string[] _designerProcessNames = new[] { "xdesproc", "devenv" };
private static bool? _runningFromVisualStudioDesigner = null;
public static bool RunningFromVisualStudioDesigner
{
get
{
if (!_runningFromVisualStudioDesigner.HasValue)
{
using (System.Diagnostics.Process currentProcess = System.Diagnostics.Process.GetCurrentProcess())
{
_runningFromVisualStudioDesigner = _designerProcessNames.Contains(currentProcess.ProcessName.ToLower().Trim());
}
}
return _runningFromVisualStudioDesigner.Value;
}
}
/// <summary>
/// Are we in design mode?
/// </summary>
/// <returns>True if in design mode</returns>
private bool IsDesignMode() {
// Ugly hack, but it works in every version
return 0 == String.CompareOrdinal(
"devenv.exe", 0,
Application.ExecutablePath, Application.ExecutablePath.Length - 10, 10);
}
System.Diagnostics.Debugger.IsAttached
It's hack-ish, but if you're using VB.NET and when you're running from within Visual Studio My.Application.Deployment.CurrentDeployment will be Nothing, because you haven't deployed it yet. I'm not sure how to check the equivalent value in C#.
using (System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess())
{
bool inDesigner = process.ProcessName.ToLower().Trim() == "devenv";
return inDesigner;
}
I tried the above code (added a using statement) and this would fail on some occasions for me. Testing in the constructor of a usercontrol placed directly in a form with the designer loading at startup. But would work in other places.
What worked for me, in all locations is:
private bool isDesignMode()
{
bool bProcCheck = false;
using (System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess())
{
bProcCheck = process.ProcessName.ToLower().Trim() == "devenv";
}
bool bModeCheck = (System.ComponentModel.LicenseManager.UsageMode == System.ComponentModel.LicenseUsageMode.Designtime);
return bProcCheck || DesignMode || bModeCheck;
}
Maybe a bit overkill, but it works, so is good enough for me.
The success in the example noted above is the bModeCheck, so probably the DesignMode is surplus.
You check the DesignMode property of your control:
if (!DesignMode)
{
//Do production runtime stuff
}
Note that this won't work in your constructor because the components haven't been initialized yet.
When running a project, its name is appended with ".vshost".
So, I use this:
public bool IsInDesignMode
{
get
{
Process p = Process.GetCurrentProcess();
bool result = false;
if (p.ProcessName.ToLower().Trim().IndexOf("vshost") != -1)
result = true;
p.Dispose();
return result;
}
}
It works for me.
I'm not sure if running in debug mode counts as real, but an easy way is to include an if statement in your code that checkes for System.Diagnostics.Debugger.IsAttached.
If you created a property that you don't need at all at design time, you can use the DesignerSerializationVisibility attribute and set it to Hidden. For example:
protected virtual DataGridView GetGrid()
{
throw new NotImplementedException("frmBase.GetGrid()");
}
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public int ColumnCount { get { return GetGrid().Columns.Count; } set { /*Some code*/ } }
It stopped my Visual Studio crashing every time I made a change to the form with NotImplementedException() and tried to save. Instead, Visual Studio knows that I don't want to serialize this property, so it can skip it. It only displays some weird string in the properties box of the form, but it seems to be safe to ignore.
Please note that this change does not take effect until you rebuild.
We use the following code in UserControls and it does the work. Using only DesignMode will not work in your app that uses your custom user controls as pointed out by other members.
public bool IsDesignerHosted
{
get { return IsControlDesignerHosted(this); }
}
public bool IsControlDesignerHosted(System.Windows.Forms.Control ctrl)
{
if (ctrl != null)
{
if (ctrl.Site != null)
{
if (ctrl.Site.DesignMode == true)
return true;
else
{
if (IsControlDesignerHosted(ctrl.Parent))
return true;
else
return false;
}
}
else
{
if (IsControlDesignerHosted(ctrl.Parent))
return true;
else
return false;
}
}
else
return false;
}
Basically the logic above boils down to:
public bool IsControlDesignerHosted(System.Windows.Forms.Control ctrl)
{
if (ctrl == null) return false;
if (ctrl.Site != null && ctrl.Site.DesignMode) return true;
return IsControlDesignerHosted(ctrl.Parent);
}
If you are in a form or control you can use the DesignMode property:
if (DesignMode)
{
DesignMode Only stuff
}
I found the DesignMode property to be buggy, at least in previous versions of Visual Studio. Hence, I made my own using the following logic:
Process.GetCurrentProcess().ProcessName.ToLower().Trim() == "devenv";
Kind of a hack, I know, but it works well.
System.ComponentModel.Component.DesignMode == true
To solve the problem, you can also code as below:
private bool IsUnderDevelopment
{
get
{
System.Diagnostics.Process process = System.Diagnostics.Process.GetCurrentProcess();
if (process.ProcessName.EndsWith(".vshost")) return true;
else return false;
}
}
Here's another one:
//Caters only to thing done while only in design mode
if (App.Current.MainWindow == null){ // in design mode }
//Avoids design mode problems
if (App.Current.MainWindow != null) { //applicaiton is running }
After testing most of the answers here, unfortunately nothing worked for me (VS2015).
So I added a little twist to JohnV's answer, which didn't work out of the box, since DesignMode is a protected Property in the Control class.
First I made an extension method which returns the DesignMode's Property value via Reflection:
public static Boolean GetDesignMode(this Control control)
{
BindingFlags bindFlags = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Static;
PropertyInfo prop = control.GetType().GetProperty("DesignMode", bindFlags);
return (Boolean)prop.GetValue(control, null);
}
and then I made a function like JohnV:
public bool HostedDesignMode
{
get
{
Control parent = Parent;
while (parent != null)
{
if (parent.GetDesignMode()) return true;
parent = parent.Parent;
}
return DesignMode;
}
}
This is the only method that worked for me, avoiding all the ProcessName mess, and while reflection should not be used lightly, in this case it did all the difference! ;)
EDIT:
You can also make the second function an extension method like this:
public static Boolean IsInDesignMode(this Control control)
{
Control parent = control.Parent;
while (parent != null)
{
if (parent.GetDesignMode())
{
return true;
}
parent = parent.Parent;
}
return control.GetDesignMode();
}
For WPF (hopefully this is useful for those WPF people stumbling upon this question):
if (System.ComponentModel.DesignerProperties.GetIsInDesignMode(new DependencyObject()))
{
}
GetIsInDesignMode requires a DependencyObject. If you don't have one, just create one.
/// <summary>
/// Whether or not we are being run from the Visual Studio IDE
/// </summary>
public bool InIDE
{
get
{
return Process.GetCurrentProcess().ProcessName.ToLower().Trim().EndsWith("vshost");
}
}
Here's a flexible way that is adaptable to where you compile from as well as whether or not you care which mode you're in.
string testString1 = "\\bin\\";
//string testString = "\\bin\\Debug\\";
//string testString = "\\bin\\Release\\";
if (AppDomain.CurrentDomain.BaseDirectory.Contains(testString))
{
//Your code here
}

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