Browse questions answered by Jon Skeet

C# / LINQ fastest way of comparing two lists and assigning value

I have made a code which basically compares two lists in C#. First list contains properties like this: ItemID TotalViews First list lacks values for TotalViews so I'm...

This is like jdweng's answer, but slightly simpler and it won't throw an exception for missing item IDs: var hitCountsById = HitCountItemIDS.ToDictionary(x => x.ItemID, x => x.HitCount); foreach (var item in parsedMerchantData) { ... more 2/20/2017 7:01:32 PM

Second iteration of XDocument.Save() throwing "Access to Path Denied"

I'm writing a small class to manage configuration XML for an in-house application. The following code is called each time a new list of t is loaded, and attempts to serialize...

I'm surprised it's working on the first iteration - because you're not checking a useful file. Instead of calling Path.Combine with multiple arguments, you're concatenating TaskData.xml with the current directory. You want: if... more 2/20/2017 6:09:47 PM

How do I deserialise different NodaTime LocalDate patterns within the same JSON object

I'm trying to use NodaTime to interpret dates retrieved from a third-party API. The dates come in an annoying array of formats in the same response, one that I'm particularly...

This does indeed seem to be a use case we hadn't considered. For "normal" usage, sealing NodaPatternConverter feels like the right approach - but when a JsonConverter has to be specified by type rather than instantiated, the sealing is... more 2/20/2017 6:02:50 PM

Why addLast() not working properly

I created a DeQueue as follws Deque<Integer> deque = new ArrayDeque<Integer>(8); // use add() method to add elements in the...

addLast doesn't somehow maintain a notion of "this should be last" forever - it just adds to the end of the current dequeue. It's equivalent to add, as documented. So if we look at the values at each step, we have: deque.add(20); //... more 2/19/2017 9:37:59 AM

Getting the actual this reference to the task state machine

I'm playing with the idea of tampering with the state of a tasks internal state machine, but i'm having trouble finding a way to actually access the state machine reference within...

It's nasty, and it's not guaranteed to work (it depends on implementation details) - but this works for me... it basically provokes the state machine to pass a continuation to an awaiter. We can then get the state machine out of the... more 2/17/2017 2:57:44 PM

What is the "Name=value" in [MyAttribute(Name=value)]

I don't know what phrasing to use to google this. Consider this attribute: [MyAttribute(MyOption=true,OtherOption=false)] What is the Name=value part? And how can I implement...

It's specifying a property when creating an instance of the attribute. Attributes can have constructor parameters and properties - this one is setting a property. Note that you can mix positional constructor arguments, named constructor... more 2/17/2017 12:06:30 PM

C# default parameter by name is this possible?

May be this is a stupid question but: I wonder if there is something like default parameter but not by value - but by name. Example: I must use a parameter "IWebDriver driver"...

No, there's no way of doing that. Default parameters have to have constant values - they can't depend on a value taken from a local variable. It sounds like you should probably construct an instance which stores a driver reference in a... more 2/17/2017 11:58:08 AM

How to copy image in java using bufferedreader/writer

File file = new File("download.png"); File newfile = new File("D:\\Java.png"); BufferedReader br=null; BufferedWriter bw=null; try { FileReader fr =...

Whats wrong with this code. You're using text-based classes for binary data. Is it possible with BufferedReader and Writer Class? Not while you're dealing with binary data, no. I know how to to make copy of image using... more 2/16/2017 3:57:55 PM

why does i.Parent.ReplaceWith(i) not throw an exception?

In these statements (running with MoreLinq): var xml = @" <div> <p> <h2>hey</h2> </p> <pre /> <h2 class=""cool"" /> <p> ...

You don't need MoreLINQ to demonstrate this at all - and you can simplify the sample code, too: using System; using System.Linq; using System.Xml.Linq; class Program { static void Main() { var element = new XElement( ... more 2/16/2017 9:15:54 AM

C# convert System.Func<Tderived, bool> to System/Func<Tbase, bool>

I've googled but couldn't find satisfactory answers. I'm basically trying to get this code to work: public List<WordEntry> WordDataBase = new...

Basically, you just need to cast - the language rules don't allow the compiler to take the if statement into account when it thinks about the types involved. Note that you also need to call ToList<Entry>(), specifying the type... more 2/15/2017 3:18:47 PM