Where to define delegates in .Net 6 Console template using top level statements? - delegates

I recently tried the .Net 6 console template, with top level statements, in Visual studio and stumbled into a Gotcha. If you try to compile the below code, Visual Studio will give a red squiggly line under the string declaration var s = "myString";. You will also receive the error: Top-level statements must precede namespace and type declarations.
delegate string StringReturner(int i);
var s = "myString";
Console.WriteLine(s);
So, what is the problem here?

The issue is that the delegate declaration has to happen after the top level statements. A delegate declaration does not count as a top level statement, but counts as a type declaration. The following code works fine:
var s = "myString";
Console.WriteLine(s);
delegate string StringReturner(int i);

Related

All Typescript Variables Are Accessible In All Files?

File A:var x: number = 5;
File B:var x = function (): number { return 5; };
Error:Subsqeuent variable declarations must have same type.
Removing all references (///<reference path='/Scripts/example.ts' />) has NO effect on my project. Everything still compiles, Intellisense still works. To my understanding, this is definitely not intended behavior. Any variable declared in any file is available in all files, like the one that caused the error above. I've been aware something weird was going on but I'm about to embark on a project where File B is going to have lots of variables of the same name as A, but they must remain separate. So this is an issue. But I can't find any reading on what's going on here. Everyone says you control Intellisense with the reference directive and you must use it.
Can't find anything about this in Project Settings>TypeScript, nor Tools>Options.
It's expected behavior. Use modules to separate variables in different files
// file 1
module First {
var x = 3;
}
// file 2
module Second {
var x = function (): number { return 5; };
}
See also TypeScript module documentation and
javascript module pattern
Another option would be using AMD or CommonJS compilation option of the TypeScript, see this article

Linq to DataSet query isn't returning expected EnumerableRowCollection<DataRow>

dtbl isn't a strongly typed DataTable, but all these nonetheless work fine (so namespaces and references appear to be ok)
EnumerableRowCollection<DataRow> a = dtbl.AsEnumerable();
DataView b = dtbl.AsDataView();
IEnumerable<DataRow> c = from y in dtbl.AsEnumerable() select y;
however, both these yield:
"Cannot implicitly convert IEnumerable to EnumerableRowCollection"
EnumerableRowCollection<DataRow> d = from y in dtbl.AsEnumerable() select y;
EnumerableRowCollection<DataRow> e = dtbl.AsEnumerable().Select(y=>y);
the error makes sense, but queries returning EnumerableRowCollection are shown in
MSDN example http://msdn.microsoft.com/en-us/library/bb669080(v=vs.110).aspx and here on
stackoverflow without apparent hiccup
this is a showstopper, so a solution would be very welcome, as I need to get to:
DataView view = (query performing filter and sort on dtbl).AsDataView();
I can't reproduce this with VS 2012 and .Net 4.5, but a work-around could be to bypass the syntactic sugar of extension methods and use the Select method directly off the static class in which it is defined:
EnumerableRowCollectionExtensions.Select(dtbl.AsEnumerable(), d => d)
See EnumerableRowCollectionExtensions Class.
SOLVED: it was an interfering extension method; I defined a list of "pass-though" extensions (Select, OrderBy, etc) to allow functions in other source files to avoid "using System.Linq", as well as allowing all Linq calls to be quickly found by reference.
Turns out there are undocumented (and apparently inaccessible) versions of the extension methods like EnumerableRowCollection.Select<>() that get hidden by the pass-throughs, and that are defined in an extension class that so far I can't find.
Anyway, I can get there from here by either finding the extension class, or yanking the pass-throughs.

Copy object values in Visual Studio debug mode

In Visual Studio debug mode it's possible to hover over variables to show their value and then right-click to "Copy", "Copy Expression" or "Copy Value".
In case the variable is an object and not just a basic type, there's a + sign to expand and explore the object. It there a way to copy all that into the clipboard?
In the immediate window, type
?name_of_variable
This will print out everything, and you can manually copy that anywhere you want, or use the immediate window's logging features to automatically write it to a file.
UPDATE: I assume you were asking how to copy/paste the nested structure of the values so that you could either search it textually, or so that you can save it on the side and then later compare the object's state to it. If I'm right, you might want to check out the commercial extension to Visual Studio that I created, called OzCode, which lets you do these thing much more easily through the "Search" and "Compare" features.
UPDATE 2 To answer #ppumkin's question, our new EAP has a new Export feature allows users to Export the variable values to Json, XML, Excel, or C# code.
Full disclosure: I'm the co-creator of the tool I described here.
You can run below code in immediate window and it will export to an xml file the serialized XML representation of an object:
(new System.Xml.Serialization.XmlSerializer(obj.GetType())).Serialize(new System.IO.StreamWriter(#"c:\temp\text.xml"), obj)
Source: Visual Studio how to serialize object from debugger
Most popular answer from https://stackoverflow.com/a/23362097/2680660:
With any luck you have Json.Net in you appdomain already. In which
case pop this into your Immediate window:
Newtonsoft.Json.JsonConvert.SerializeObject(someVariable)
Edit: With .NET Core 3.0, the following works too:
System.Text.Json.JsonSerializer.Serialize(someVariable)
There is a extension called Object Exporter that does this conveniently.
http://www.omarelabd.net/exporting-objects-from-the-visual-studio-debugger/
Extension: https://visualstudiogallery.msdn.microsoft.com/c6a21c68-f815-4895-999f-cd0885d8774f
You can add a watch for that object, and in the watch window, expand and select everything you want to copy and then copy it.
By using attributes to decorate your classes and methods you can have a specific value from your object display during debugging with the DebuggerDisplay attribute e.g.
[DebuggerDisplay("Person - {Name} is {Age} years old")]
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
}
I always use:
string myJsonString = JsonConvert.SerializeObject(<some object>);
Then I copy the string value which unfortunately also copies the back slashes.
To remove the backlashes go here:
https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_replace
Then within the <p id="demo">Visit Microsoft!</p> element replace the text with the text you copied.
then replace the var res = str.replace("Microsoft", "W3Schools"); line with
var res = str.replace(/\\/g, '')
Run these new changes but don't forget to click the "try it" button on the right.
Now you should have all the text of the object in json format that you can drop in a json formatter like http://jsonformatter.org or to create a POCO you can now use http://json2csharp.com/
ObjectDumper.NET
This is an awesome way!
You probably need this data for a unit test, so create a Sandbox.cs temporary test or you can create a Console App.
Make sure to get NuGet package, ObjectDumper.NET, not ObjectDumper.
Run this test (or console app)
View test output or text file to get the C# initializer code!
Code:
[TestClass]
public class Sandbox
{
[TestMethod]
public void GetInitializerCode()
{
var db = TestServices.GetDbContext();
var list = db.MyObjects.ToList();
var literal = ObjectDumper.Dump(list, new DumpOptions
{
DumpStyle = DumpStyle.CSharp,
IndentSize = 4
});
Console.WriteLine(literal); // Some test runners will truncate this, so use the file in that case.
File.WriteAllText(#"C:\temp\dump.txt", literal);
}
}
I used to use Object Exporter, but it is 5 years old and no longer supported in Visual Studio. It seems like Visual Studio Extensions come and go, but let's hope this NuGet package is here to stay! (Also it is actively maintained as of this writing.)
Google led me to this 8-year-old question and I ended up using ObjectDumper to achieve something very similar to copy-pasting debugger data. It was a breeze.
I know the question asked specifically about information from the debugger, but ObjectDumper gives information that is basically the same. I'm assuming those who google this question are like me and just need the data for debugging purposes and don't care whether it technically comes from the debugger or not.
I know I'm a bit late to the party, but I wrote a JSON implementation for serializing an object, if you prefer to have JSON output. Uses Newtonsoft.Json reference.
private static void WriteDebugJSON (dynamic obj, string filePath)
{
using (StreamWriter d = new StreamWriter(filePath))
{
d.Write(JsonConvert.SerializeObject(obj));
}
}
I've just right clicked on the variable and selected AddWatch, that's bring up watch window that consists of all the values. I selected all and paste it in a text a text editor, that's all.
Object Dumper is a free and open source extension for Visual Studio and Visual Studio Code.
"Dump as" commands are available via context menu in the Code and Immediate windows.
It's exporting objects to:
C# object initialization code,
JSON,
Visual Basic object initialization code,
XML,
YAML.
I believe that combined with the Diff tool it can be helpful.
I'm the author of this tool.
if you have a list and you want to find a specific variable:
In the immediate window, type
myList.Any(s => s.ID == 5062);
if this returns true
var myDebugVar = myList.FirstOrDefault(s => s.ID == 5062);
?myDebugVar
useful tips here, I'll add my preference for when i next end up here asking this question again in the future.
if you don't mind adding an extension that doesn't require output files or such there's the Hex Visualizer extension for visual studio, by mladen mihajlovic, he's done versions since 2015.
provides a nice display of the array via the usual magnifine glass view object from the local variables window.
https://marketplace.visualstudio.com/items?itemName=Mika76.HexVisualizer2019 is the 2019 version.
If you're in debug mode, you can copy any variable by writing copy() in the debug terminal.
This works with nested objects and also removes truncation and copies the complete value.
Tip: you can right click a variable, and click Copy as Expression and then paste that in the copy-function.
System.IO.File.WriteAllText("b.json", page.DebugInfo().ToJson())
Works great to avoid to deal with string debug format " for quote.
As #OmerRaviv says, you can go to Debug → Windows → Immediate where you can type:
myVariable
(as #bombek pointed out in the comments you don't need the question mark) although as some have found this limits to 100 lines.
I found a better way was to right click the variable → Add Watch, then press the + for anything I wanted to expand, then used #GeneWhitaker's solution, which is Ctrl+A, then copy Ctrl+C and paste into a text editor Ctrl+V.

Break when a value changes using the Visual Studio debugger

Is there a way to place a watch on variable and only have Visual Studio break when that value changes?
It would make it so much easier to find tricky state issues.
Can this be done?
Breakpoint conditions still need a breakpoint set, and I'd rather set a watch and let Visual Studio set the breakpoints at state changes.
In the Visual Studio 2005 menu:
Debug -> New Breakpoint -> New Data Breakpoint
Enter:
&myVariable
You can also choose to break explicitly in code:
// Assuming C#
if (condition)
{
System.Diagnostics.Debugger.Break();
}
From MSDN:
Debugger.Break:
If no debugger is attached, users are
asked if they want to attach a
debugger. If yes, the debugger is
started. If a debugger is attached,
the debugger is signaled with a user
breakpoint event, and the debugger
suspends execution of the process just
as if a debugger breakpoint had been
hit.
This is only a fallback, though. Setting a conditional breakpoint in Visual Studio, as described in other comments, is a better choice.
In Visual Studio 2015, you can place a breakpoint on the set accessor of an Auto-Implemented Property and the debugger will break when the property is updated
public bool IsUpdated
{
get;
set; //set breakpoint on this line
}
Update
Alternatively; #AbdulRaufMujahid has pointed out in the comments that if the auto implemented property is on a single line, you can position your cursor at the get; or set; and hit F9 and a breakpoint will be placed accordingly. Nice!
public bool IsUpdated { get; set; }
Imagine you have a class called A with the following declaration.
class A
{
public:
A();
private:
int m_value;
};
You want the program to stop when someone modifies the value of "m_value".
Go to the class definition and put a breakpoint in the constructor of A.
A::A()
{
... // set breakpoint here
}
Once we stopped the program:
Debug -> New Breakpoint -> New Data Breakpoint ...
Address: &(this->m_value)
Byte Count: 4 (Because int has 4 bytes)
Now, we can resume the program. The debugger will stop when the value is changed.
You can do the same with inherited classes or compound classes.
class B
{
private:
A m_a;
};
Address: &(this->m_a.m_value)
If you don't know the number of bytes of the variable you want to inspect, you can use the sizeof operator.
For example:
// to know the size of the word processor,
// if you want to inspect a pointer.
int wordTam = sizeof (void* );
If you look at the "Call stack" you can see the function that changed the value of the variable.
Change the variable into a property and add a breakpoint in the set method. Example:
private bool m_Var = false;
protected bool var
{
get {
return m_var;
}
set {
m_var = value;
}
}
Update in 2019:
This is now officially supported in Visual Studio 2019 Preview 2 for .Net Core 3.0 or higher. Of course, you may have to put some thoughts in potential risks of using a Preview version of IDE. I imagine in the near future this will be included in the official Visual Studio.
https://blogs.msdn.microsoft.com/visualstudio/2019/02/12/break-when-value-changes-data-breakpoints-for-net-core-in-visual-studio-2019/
Fortunately, data breakpoints are no longer a C++ exclusive because they are now available for .NET Core (3.0 or higher) in Visual Studio 2019 Preview 2!
If you are using WPF, there is an awesome tool : WPF Inspector.
It attaches itself to a WPF app and display the full tree of controls with the all properties, an it allows you (amongst other things) to break on any property change.
But sadly I didn't find any tool that would allow you to do the same with ANY property or variable.
I remember the way you described it using Visual Basic 6.0. In Visual Studio, the only way I have found so far is by specifying a breakpoint condition.
Right click on the breakpoint works fine for me (though mostly I am using it for conditional breakpoints on specific variable values. Even breaking on expressions involving a thread name works which is very useful if you're trying to spot threading issues).
As Peter Mortensen wrote:
In the Visual Studio 2005 menu:
Debug -> New Breakpoint -> New Data Breakpoint
Enter: &myVariable
Additional information:
Obviously, the system must know which address in memory to watch.
So
- set a normal breakpoint to the initialisation of myVariable (or myClass.m_Variable)
- run the system and wait till it stops at that breakpoint.
- Now the Menu entry is enabled, and you can watch the variable by entering &myVariable,
or the instance by entering &myClass.m_Variable. Now the addresses are well defined.
Sorry when I did things wrong by explaining an already given solution. But I could not add a comment, and there has been some comments regarding this.
You can use a memory watchpoint in unmanaged code. Not sure if these are available in managed code though.
You can probably make a clever use of the DebugBreak() function.
You can optionally overload the = operator for the variable and can put the breakpoint inside the overloaded function on specific condition.

Is there a way to specify outlining defaults in Visual Studio 2008 so that a file opens up with members collapsed by default?

What I would like to do is have VS2008, when I open a code file, collapse all members of the classes/interfaces in the file by default (including, crucially, any XML documentation and comments).
I do not want to use regions, at all.
I would also like to be able to use the ctrl+m, ctrl+l chord to toggle all member outlining (for example, if everything is collapsed, I would like it to expand all of the members, but not the comments or XML documentation).
Possible? How?
Yes to part 1.
Unsure about part 2.
To have VS2008 automatically open files in a Collapsed state you'll need to create an addin to run the "Edit.CollapsetoDefinition" when each document opens.
This isn't overly tricky - The difficult parts seems to be the that you have to run the code a few milliseconds after the document is actually opened so you need to use the threed pool to do that.
Create an Addin project for VS2008.
Add this code (see following) to the end of the OnConnection Method of the Connect class.
switch (connectMode)
{
case ext_ConnectMode.ext_cm_UISetup:
case ext_ConnectMode.ext_cm_Startup:
//Do nothing OnStartup will be called once IDE is initialised.
break;
case ext_ConnectMode.ext_cm_AfterStartup:
//The addin was started post startup so we need to call its initialisation manually
InitialiseHandlers();
break;
}
Add this method to the Connect class
private void InitialiseHandlers()
{
this._openHandler = new OnOpenHandler(_applicationObject);
}
Add a call to InitialiseHandlers() to the OnStartupComplete method of the Connect class.
public void OnStartupComplete(ref Array custom)
{
InitialiseHandlers();
}
Add this class to the project.
using System;
using System.Collections.Generic;
using System.Text;
using EnvDTE80;
using EnvDTE;
using System.Threading;
namespace Collapser
{
internal class OnOpenHandler
{
DTE2 _application = null;
EnvDTE.Events events = null;
EnvDTE.DocumentEvents docEvents = null;
internal OnOpenHandler(DTE2 application)
{
_application = application;
events = _application.Events;
docEvents = events.get_DocumentEvents(null);
docEvents.DocumentOpened +=new _dispDocumentEvents_DocumentOpenedEventHandler(OnOpenHandler_DocumentOpened);
}
void OnOpenHandler_DocumentOpened(EnvDTE.Document document)
{
if (_application.Debugger.CurrentMode != dbgDebugMode.dbgBreakMode)
{
ThreadPool.QueueUserWorkItem(new WaitCallback(Collapse));
}
}
private void Collapse(object o)
{
System.Threading.Thread.Sleep(150);
_application.ExecuteCommand("Edit.CollapsetoDefinitions", "");
}
}
}
And now all opened files should be fully collapsed.
It would be much easier to use the Visual Studio Macros to do the same thing. Editing the "EnvironmentEvents" Macro file in MyMacros and adding a handler for DocumentEvents.DocumentOpened with :
DTE.ExecuteCommand("Edit.CollapsetoDefinitions")
A quick way to collapse all outlining to function-definitions is to press:
Contextmenu-button*(next to your right windows button)*, L, O
I use it all the time. If there is a real hotkey for this please tell me :)
I had tried working out some Visual Basic code for a macro myself, borrowing from different places, and couldn't get anything to work. So what did I do? Why, I asked a question on StackOverflow of course! It got answered, I added the suggested code to my EnvironmentEvents macro, and now when I open CS files, after about a second, all my definitions are collapsed. :)

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