.NET Megathread 3.5: await GetGoodPosts()

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CapnAndy: Feb 27, 2004; Some teeth long for ripping, gleaming wet from black dog gums. So you keep your eyes closed at the end. You don't want to see such a mouth up close. before the bite, before its oblivion in the goring of your soft parts, the speckled lips will curl back in a whinny of excitement. You just know it.

So today I learned that HttpWebResponse throws an error on 404 and you have to wrap the whole thing in try/catch and you can use the exception's response code in the catch segment.

CHECKING TO SEE IF THE WEBSITE IS THERE IS EXACTLY WHAT I'M USING YOU FOR, YOU STUPID CALL, WHY DO YOU NOT KNOW HOW TO HANDLE loving 404S

I just needed to vent.

# ? Sep 8, 2015 22:20

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# ? May 17, 2024 10:22

Potassium Problems: Sep 28, 2001

CapnAndy posted:

So today I learned that HttpWebResponse throws an error on 404 and you have to wrap the whole thing in try/catch and you can use the exception's response code in the catch segment.

CHECKING TO SEE IF THE WEBSITE IS THERE IS EXACTLY WHAT I'M USING YOU FOR, YOU STUPID CALL, WHY DO YOU NOT KNOW HOW TO HANDLE loving 404S

I just needed to vent.

It also throws an exception on 304 Not Modified! I hated seeing "The remote server returned an error: 304 (Not Modified)" because the server wasn't in the wrong :argh:

If you have the option, using HttpClient in System.Net.Http (.NET 4.5 I think?) is much better.

# ? Sep 8, 2015 22:28

CapnAndy: Feb 27, 2004; Some teeth long for ripping, gleaming wet from black dog gums. So you keep your eyes closed at the end. You don't want to see such a mouth up close. before the bite, before its oblivion in the goring of your soft parts, the speckled lips will curl back in a whinny of excitement. You just know it.

Lone_Strider posted:

It also throws an exception on 304 Not Modified! I hated seeing "The remote server returned an error: 304 (Not Modified)" because the server wasn't in the wrong If you have the option, using HttpClient in System.Net.Http (.NET 4.5 I think?) is much better.

3.5, so I don't have the option.

If the exception has a recognizable response code why are you throwing exceptions, you know exactly what those responses are you stupid call.

# ? Sep 8, 2015 22:29

brap: Aug 23, 2004; Grimey Drawer

Yeah it's an insanely stupid system. I think the ASP.NET 5 stuff doesn't do this. I also love returning a 503 by throwing a loving exception.

Exceptions are maybe the most misused concept in high-level languages.

# ? Sep 9, 2015 00:59

kitten emergency: Jan 13, 2008; get meow this wack-ass crystal prison

ASP.NET 5 is much smarter about pretty much everything involving response codes.

# ? Sep 9, 2015 01:21

LOOK I AM A TURTLE: May 22, 2003; "I'm actually a tortoise."; Grimey Drawer

These are textbook examples of what Eric Lippert calls vexing exceptions. I must admit I've made the same mistake in my own code many times, and I continue to do it sometimes because I'm stupid and forget, but I also have yet to design APIs used by what might be literally millions of developers.

# ? Sep 9, 2015 11:26

epswing: Nov 4, 2003; Soiled Meat

I have some stream processing questions. I'm just muddling my way through using docs/example. I don't have the code in front of me at the moment so please forgive syntax errors.

Say I have a method which writes from input to output:

C# code:

void Process(Stream input, Stream output)
{
	using (var reader = new StreamReader(input))
	using (var writer = new StreamWriter(output))
	{
		while (reader.Peek() >= 0)
		{
			writer.Write(reader.Read());
		}
	}
}

The caller might look something like this:

C# code:

using (var fileInput = File.OpenRead(source))
using (var fileOutput = File.OpenWrite(dest))
{
	Process(fileInput, fileOutput);
}

This pretty much works as I expect. Now what if I had several Process-like methods? Conceptually I want to do something like this:

C# code:

using (var fileInput = File.OpenRead(source))
using (var tmp1 = new MemoryStream())
using (var tmp2 = new MemoryStream())
using (var fileOutput = File.OpenWrite(dest))
{
	ProcessA(fileInput, tmp1);
	ProcessB(tmp1, tmp2);
	ProcessC(tmp2, fileOutput);
}

I want to be able to write my ProcessX methods without knowing (or caring) where the stream came from, or where it's going. However I'm running into "stream closed" and "stream not readable" errors. Do I need to seek to the beginning of input streams?

Edit: now that I'm looking at all these using statements, I get the feeling that by saying using (var writer = new StreamWriter(output)) the StreamWriter will close the Stream before the method returns, and when I use output later, it blows up.

epswing fucked around with this message at 21:56 on Sep 9, 2015

# ? Sep 9, 2015 21:54

Potassium Problems: Sep 28, 2001

Nope, the streams get disposed of when the code exits the using block (assuming you're not manually disposing of them in your methods). You're correct in that you need to start each Process method with a seek on the input stream back to its beginning, assuming the streams support seeking.

Edit: whoops, you're right, you need to get rid of the using blocks in your Process methods. They'll kill the streams for sure.

Potassium Problems fucked around with this message at 22:27 on Sep 9, 2015

# ? Sep 9, 2015 22:25

epswing: Nov 4, 2003; Soiled Meat

Right! Makes sense. Removing the using statements from Process methods did the trick.

epswing fucked around with this message at 22:46 on Sep 9, 2015

# ? Sep 9, 2015 22:29

Bognar: Aug 4, 2011; I am the queen of France; Hot Rope Guy

epalm posted:

Right! Makes sense. Removing the using statements from Process methods did the trick.

While that will work, that's not the most appropriate solution. Using IDisposables without using blocks looks like a bad thing, even though it may not be. Future developers may be tempted to wrap them with a using, which will cause a non-obvious bug.

My preferred solution is to use this StreamReader overload and pass true to the last parameter, leaveOpen. There is a similar StreamWriter overload.

# ? Sep 10, 2015 14:17

The MUMPSorceress: Jan 6, 2012; ^SHTPSTS; Gary’s Answer

Can someone explain DateTime.now to me? I thought it was just the number of ticks since the epoch stored in a long, but I'm getting key collisions when trying to use it as a key in a dictionary. This code is from an educational project at work, so I'm required to be able to return the collection items in the order they were added. Using an array or linked list isn't allowed because removal is too slow, so instead I have to use a dictionary. I'm aware that it's the kinda thing that doesn't matter in a typical use case, but that's the "discovery" they want you to make on this project (that if you use a list you fail the unit tests for efficiency).

Basically, we have this item class and this inventory class, the the inventory needs to be able to efficiently loop over the items in both order added and alphabetical order by name. To do this we basically have 2 dicitonaries. One with names as keys and one with *something* as keys that keeps things in chron order.
Anyway, here's the code I eventually used that works:

C# code:

//Pieces of Item class
//The collection has a long field that increments each time a new item is added. That value is placed into this field so
//you can find it in the name dictionary and then use Added to remove it from the chron dictionary
public long Added { get; set; }

//Pieces from the Inventory class
private InstrumentedDictionary<long, Item> _chronDict;
private InstrumentedDictionary<string, Item> _prodDict;
private long _chronKey = 0;

//Note that the method signature was part of the specification
public void Add(Item toAdd)
        {
            if (_prodDict.ContainsKey(toAdd.Name))
            {
                throw new DuplicateProductNameException(toAdd.Name);
            }
            else
            {
                toAdd.Added = ++_chronKey;
                _chronDict.Add(toAdd.Added, toAdd);
                _prodDict.Add(toAdd.Name,toAdd);
                //some other bookkeeping ...
            }
        }
//Again, method signature specified for me
public void Remove(Item toRemove)
        {
            if (!_prodDict.ContainsKey(toRemove.Name))
            {
                throw new KeyNotFoundException();
            }
            else
            {
               //bookkeeping
                _prodDict.Remove(toRemove.Name);
                _chronDict.Remove(toRemove.Added); //here you can see where the added field comes into play
                 //bookkeeping
            }
        }

Now, this works fine, but I had wanted to be slicker. I initially tried to use DateTime.Now as the key for each new item instead. Since each time I assign that value to a long it should be higher, I figured this was an easy way of not only having chronologically ordered keys, but having the keys themselves be meaningful chronologically. The end result, though, was that every item after the first added to the collection just causes a key collision error. Here's how my first code looked. I later changed it to cast Now to a long and store it as a long, but I initially did it with DateTimes. Neither way worked:

C# code:

//Pieces of Item class
//The collection has a long field that increments each time a new item is added. That value is placed into this field so
//you can find it in the name dictionary and then use Added to remove it from the chron dictionary
public DateTime Added { get; set; }

//Pieces from the Inventory class
private InstrumentedDictionary<DateTime, Item> _chronDict;
private InstrumentedDictionary<string, Item> _prodDict;

//Note that the method signature was part of the specification
public void Add(Item toAdd)
        {
            if (_prodDict.ContainsKey(toAdd.Name))
            {
                throw new DuplicateProductNameException(toAdd.Name);
            }
            else
            {
                toAdd.Added = DateTime.Now;
                _chronDict.Add(toAdd.Added, toAdd);
                _prodDict.Add(toAdd.Name,toAdd);
                //some other bookkeeping ...
            }
        }
//Again, method signature specified for me
public void Remove(Item toRemove)
        {
            if (!_prodDict.ContainsKey(toRemove.Name))
            {
                throw new KeyNotFoundException();
            }
            else
            {
               //bookkeeping
                _prodDict.Remove(toRemove.Name);
                _chronDict.Remove(toRemove.Added); //here you can see where the added field comes into play
                 //bookkeeping
            }
        }

To my eyes, this should work. Is there some nuance to DateTime that I'm not getting here?

# ? Sep 10, 2015 18:18

Munkeymon: Aug 14, 2003; Motherfucker's got an
armor-piercing crowbar! Rigoddamndicu𝜆ous.

Would https://msdn.microsoft.com/en-us/library/System.Collections.Specialized.OrderedDictionary(v=VS.110).aspx help or is the point that you're supposed to make something like it yourself?

# ? Sep 10, 2015 18:30

The MUMPSorceress: Jan 6, 2012; ^SHTPSTS; Gary’s Answer

Munkeymon posted:

Would https://msdn.microsoft.com/en-us/library/System.Collections.Specialized.OrderedDictionary(v=VS.110).aspx help or is the point that you're supposed to make something like it yourself?

Yeah, we have to use the dictionary class provided. I'm more just confused about DateTime.Now. I already handed in working solution with the incrementing long.

It seems that ticks are less granular than I thought. I just wrote this code:

C# code:

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int i = 1; i <= 20; i++)
            {
                Console.WriteLine(DateTime.Now.Ticks);
            }
            Console.ReadLine();
        }
    }
}

And this was the output:

code:

635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731
635774850476860731

What's the granularity of a tick?

# ? Sep 10, 2015 18:33

New Yorp New Yorp: Jul 18, 2003; Only in Kenya.; Pillbug

DateTime isn't intended for high-resolution timing. Don't use it for that.

It's system-dependent. Per http://stackoverflow.com/questions/2143140/c-sharp-datetime-now-precision,

quote:

DateTime's precision is somewhat specific to the system it's being run on. The precision is related to the speed of a context switch, which tends to be around 15 or 16 ms. (On my system, it is actually about 14 ms from my testing, but I've seen some laptops where it's closer to 35-40 ms accuracy.)

Also keep in mind that DateTime.Now represents a dependency that makes it impossible to effectively unit test your code.

# ? Sep 10, 2015 18:36

Munkeymon: Aug 14, 2003; Motherfucker's got an
armor-piercing crowbar! Rigoddamndicu𝜆ous.

LeftistMuslimObama posted:

What's the granularity of a tick?

https://msdn.microsoft.com/en-us/library/system.datetime.ticks(v=vs.110).aspx posted:

A single tick represents one hundred nanoseconds or one ten-millionth of a second. There are 10,000 ticks in a millisecond, or 10 million ticks in a second.

But there's no guarantee that it's monotonically increasing, which is what you need because a modern CPU can do more than 10 million things in a second. I don't see anything like that available without dipping into the Windows API. https://msdn.microsoft.com/en-us/library/ms724408(VS.85).aspx https://msdn.microsoft.com/en-us/library/ms644904(VS.85).aspx

# ? Sep 10, 2015 18:42

The MUMPSorceress: Jan 6, 2012; ^SHTPSTS; Gary’s Answer

Cool. I think for this just maintaining a counter myself was the simplest/best choice then. I have this problem where I feel like my simple solutions are too obvious and think there has to be a more "elegant" way to do things. I run into walls that way much too often. I need to get more confident in my solutions.

# ? Sep 10, 2015 18:45

Munkeymon: Aug 14, 2003; Motherfucker's got an
armor-piercing crowbar! Rigoddamndicu𝜆ous.

Yeah, I made a cache with a size limit for fun a while back and tried to do the same thing and the tests failed for the same reason but I didn't even thinking about using a simple incrementing number first. It happens.

# ? Sep 10, 2015 18:53

crashdome: Jun 28, 2011

This reminds me of a funny story about a program written long ago that stupidly used DateTime.Now client-side to timestamp when a new job was added by a user (yes, I was the culprit who wrote it). The PCs were domain joined and faithfully got their NTP syncs from the domain controller. As a result, everything was fine for a very long time and then one day a PC decided to go off the playground and run its time as 1970 (or something really old) for reasons I don't remember. Because the application also loaded jobs into a schedule by the scheduling assistant on another PC based on that timestamp, all of the jobs added by the first user that day showed up first and was marked as high priority and over 30 years overdue. Almost broke the system if it wasn't for the fact that as humans we often question oddities like that and the scheduling assistant brought it up to the manager who then informed me and I had to manually adjust the timestamps.

An update was done to instead use SQL's version of it during the insert instead. Since they only had one SQL server for that application and it had a pretty reliable time sync, it was felt "good enough for the time being".

I try not to think about it any more but, back then I must have spent days trying to come up with a simple but, reliable sense of coordinating time over an entire system/application and/or verifying it to appease the managers that "Yes, we can guarantee something like this will never happen again" - which is ludicrous because you can't guarantee that at all. Storing a master timestamp in a database, checking offsets, etc... then I realized just how fragile the concept of time is and my brain almost melted. Now I don't think about it and just use the best case for the scenario and hope nothing stupid ever happens. ...And if it does I shift the blame as system mismanagement.

# ? Sep 10, 2015 19:12

JawnV6: Jul 4, 2004; So hot ...

crashdome posted:

I realized just how fragile the concept of time is and my brain almost melted.

I built a system that had to maintain a RTC over 10 years on a processor with 512b of RAM connected to the server over GSM, which has unreliable timestamps. At one point I had a network timestamp, device timestamp, and GSM timestamp. None were within a minute of each other.

On the stupid DAQ I've built up now, I'm using this snippet to get millis-since-epoch:
string timestamp = (DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalMilliseconds.ToString();

In one sense sub-15ms precision doesn't matter, the sensor has it's own rate and I can detect what sample frame it's returning. I'm logging another thing, but it's on the same PC and events are several seconds long. But the discussion upthread gives me some doubt about the sensitivity to a context switch, is it having to switch over to get the time or can I assume that snippet called in a 200ms timer is relatively accurate?

# ? Sep 10, 2015 21:13

Essential: Aug 14, 2003

I found this extension a while back when I needed to get an epoch date. In my case I'm lucky in that I don't care about the time, simply just converting the date to epoch:

code:

        internal static long GetUnixEpoch(this DateTime dateTime)
        {
            var unixTime = dateTime.ToUniversalTime() -
                new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);

            return (long)unixTime.TotalSeconds;
        }

Jon Skeet has created http://nodatime.org/ , I've never used it but it may have something more akin to what you guys are trying to do.

# ? Sep 10, 2015 21:26

dougdrums: Feb 25, 2005; CLIENT REQUESTED ELECTRONIC FUNDING RECEIPT (FUNDS NOW)

crashdome posted:

... then I realized just how fragile the concept of time is and my brain almost melted.

Oh lord, I'm taking a course on this and it gets out of hand reeeal quick, if you're curious: http://plato.stanford.edu/entries/logic-temporal/#LinTimTemLogLTL

# ? Sep 10, 2015 21:46

Night Shade: Jan 13, 2013; Old School

Munkeymon posted:

But there's no guarantee that it's monotonically increasing, which is what you need because a modern CPU can do more than 10 million things in a second. I don't see anything like that available without dipping into the Windows API. https://msdn.microsoft.com/en-us/library/ms724408(VS.85).aspx https://msdn.microsoft.com/en-us/library/ms644904(VS.85).aspx

System.Diagnostics.Stopwatch uses QueryPerformanceFrequency etc. if it's available, and has static properties for whether it's a high resolution timer and how many stopwatch ticks are in a second. On this PC it claims to be high resolution with ~3.3 million stopwatch ticks per second.

Even that isn't high enough resolution for the following loop to run forever (it's terminating after 2-3 iterations usually):

code:

var sw = new Stopwatch();
sw.Start();
HashSet<TimeSpan> hs = new HashSet<TimeSpan>();
while (hs.Add(sw.Elapsed)){}
Console.WriteLine(hs.Count);

# ? Sep 10, 2015 23:30

epswing: Nov 4, 2003; Soiled Meat

Bognar posted:

My preferred solution is to use this StreamReader overload and pass true to the last parameter, leaveOpen. There is a similar StreamWriter overload.

Thanks for this nugget of wisdom.

# ? Sep 11, 2015 02:15

epswing: Nov 4, 2003; Soiled Meat

Azure question:

After adding a 2nd Web App (which was later deleted), a new resource entered the picture called "Default1". It appears to be an "App Service plan", though I'm not sure what that means. It has CPU and Memory metrics. My lone Web App seems to point to Default1.

My question is, what exactly is this App Service plan? If I create more Web Apps, will they reside under Default1? Should WebApp-to-AppServicePlan be 1:1?

# ? Sep 11, 2015 02:20

Gul Banana: Nov 28, 2003

i'm very glad to see this issue being worked on: NuGet.exe install 3.2 makes multiple unnecessary network calls
when your latency to nuget servers is 300-500 ms, the number of calls makes a very large difference.

# ? Sep 11, 2015 12:17

pepito sanchez: Apr 3, 2004; I'm not mexican

this has probably already been answered in this thread, but could someone give me a simple way of using functions in a F# library from any C# program? i've been getting into F# and love it, but i've yet to actually use it for anything practical.

# ? Sep 12, 2015 01:18

Horn: Jun 18, 2004; Penetration is the key to success; College Slice

Have you tried just adding the F# library as a reference? I'm doing it at work and there isn't anything special.

https://stackoverflow.com/questions/478531/call-f-code-from-c-sharp

# ? Sep 12, 2015 01:24

Uziel: Jun 28, 2004; Ask me about losing 200lbs, and becoming the Viking God of W&W.

pepito sanchez posted:

this has probably already been answered in this thread, but could someone give me a simple way of using functions in a F# library from any C# program? i've been getting into F# and love it, but i've yet to actually use it for anything practical.

https://github.com/cmgross/NasgaMe/blob/master/NasgaMe/Utility/BusinessLayer.cs
Check the last method in the file, it calls my F# web scraper. It was my first time using F#

# ? Sep 12, 2015 01:54

OneEightHundred: Feb 28, 2008; Soon, we will be unstoppable!

Just to be sure I'm not missing the entire point:

Is it true that there's no way that a generic class can be extended more than once? i.e. in C++ it's possible to do so with specialization to create terminal classes, but it looks like in .NET languages, there's no way to do that in a way that isn't circular, right?

OneEightHundred fucked around with this message at 04:08 on Sep 13, 2015

# ? Sep 13, 2015 04:03

Gul Banana: Nov 28, 2003

could you please give an example of the C++ idiom you mean?

# ? Sep 13, 2015 09:02

Mr Shiny Pants: Nov 12, 2012

I just wanted to say that Xamarin is awesome and that it is a crying shame that they have to show Microsoft how you do cross platform development.

WTF is up with Cordova and the other stuff? Seems like a waste of resources when Xamarin, a much smaller company, has ported XAML to about every device and you can use it to build pretty much awesome apps straight off.

I just created a new project and loaded in my PCL from my WinRT app, hooked up the viewmodels from the PCL into an IOS Xamarin forms project and it works...... drag to refresh everything.

Pretty amazing.

Now I am rebuilding my WinRT app to a Xamarin forms store application and have the benefit of it running on pretty much any device I want.

Mr Shiny Pants fucked around with this message at 15:11 on Sep 13, 2015

# ? Sep 13, 2015 15:03

Bognar: Aug 4, 2011; I am the queen of France; Hot Rope Guy

OneEightHundred posted:

Just to be sure I'm not missing the entire point:

Is it true that there's no way that a generic class can be extended more than once? i.e. in C++ it's possible to do so with specialization to create terminal classes, but it looks like in .NET languages, there's no way to do that in a way that isn't circular, right?

Not sure if I understood you correctly, but do you mean something like this?

https://dotnetfiddle.net/YnLcHc

# ? Sep 13, 2015 15:50

ether: May 20, 2001

OneEightHundred posted:

Just to be sure I'm not missing the entire point:

Is it true that there's no way that a generic class can be extended more than once? i.e. in C++ it's possible to do so with specialization to create terminal classes, but it looks like in .NET languages, there's no way to do that in a way that isn't circular, right?

code:

  public class Test<T> where T : class
  {
  }

  public interface IMoreSpecific
  {
  }

  public class Test<T> where T : IMoreSpecific
  {
  }

Like this you mean? (which obviously doesn't work)

.NET generics don't allow for multiple implementations for a generic class due to how the type-system works. Your generic class has to have a unique name.

That said you might be able to mock up a similar working concept with interfaces and a factory that's able to figure out which implementation to pick for which specific case. The implementations would have to have be named differently though.

Keep in mind that templates and generics are similar but very different at the same time.

# ? Sep 13, 2015 15:58

OneEightHundred: Feb 28, 2008; Soon, we will be unstoppable!

Gul Banana posted:

could you please give an example of the C++ idiom you mean?

Recursive templates, basically. As an example of why it'd be used, a covariant ref type in C++ could be implemented as:

code:

template<class T> struct ParentResolver { };

class Root
{
};

class Derived : public Root
{
};

template<> struct ParentResolver<Derived> { typedef Root Type; };

template<class T>
class Ref : Ref<typename ParentResolver<T>::Type>
{
    T *Get() { return static_cast<T*>(this->ptr); }
};

template<> class Ref<Root> { Root *ptr; };

In this case, Ref inherits recursively and Ref<Root> terminates it.

As far as I can tell, doing this or anything like it isn't possible without dependent type names, specializations, or deriving from a type parameter, none of which .NET generics allow, which I think rules out any way that a generic could ever inherit from another instance of the same generic. It looks like that's deliberate, but I'm just trying to confirm that's actually the case and there's not some crazy way of doing it that I'm not thinking of.

(To be clear: The point of this isn't to implement generic covariance in .NET and I know that .NET 4 supports those, the point is that I'm trying to do something that will fail miserably if this assumption isn't accurate.)

# ? Sep 13, 2015 16:43

Gul Banana: Nov 28, 2003

i see. probably the closest .NET idiom is its equivalent of curiously recurring templates:
class Base<TSelf> where TSelf : Base<TSelf> { }
class Derived : Base<Derived> { }

e.g. a generic can be *constrained* by itself, but no, they can never inherit from themselves, and there are no associated types/type members. so you should be safe to do whatever odd thing is depending on that.

# ? Sep 13, 2015 20:24

NihilCredo: Jun 6, 2011; iram omni possibili modo preme:
plus una illa te diffamabit, quam multæ virtutes commendabunt

So, let's say I have a SQL table of a few thousand rows that I want to store in memory, as it will be frequently and randomly accessed. The table has only 6-7 relevant columns, all short strings or numbers.

In the business logic, each row translates to an instance of a class which isn't quite a POCO, since it features a Parent property that returns (lazily) the instance identified by the ParentID column, plus a few static methods to find common ancestors and the like. (The fact that the class is self-referential is important, since otherwise I could have made it a struct.)

Am I more likely to be better off :

A) loading the table into memory as a DataTable and, when necessary, grabbing the row by the provided Id and instantiating the class from the row (and then throwing it away)

or

B) immediately loading the table into memory as a big Dictionary of string -> class

?

# ? Sep 14, 2015 12:35

SirViver: Oct 22, 2008

I'd say B), because a dictionary of class instances is not going to be any bigger/worse than a DataTable full of DataRows. As a benefit, the Parent property can then also do a lazy but fast lookup in the same dictionary. Just make sure the class properties are read only, so you can't gently caress up your cache by accident.

# ? Sep 14, 2015 13:43

Bognar: Aug 4, 2011; I am the queen of France; Hot Rope Guy

If your goal is to just cache a few thousand objects, then yeah pay the (minor) upfront cost of instantiating everything and loading it into a dictionary.

# ? Sep 14, 2015 14:10

Mr Shiny Pants: Nov 12, 2012

So a conceptual question about viewmodels in apps.

Let's say I have a viewmodel that has a collection and this collection contains other viewmodels, if you click an item in the collection a new view is loaded and the selected viewmodel in the collection is the datacontext for the newly opened view.

How do you handle resuming of the application in a hierarchy like this?

Worst case scenario is that the complete viewmodel is unloaded and needs to be re-instantiated again but if the app is paused on a particular view how do I figure out what I need to load again?

Should I just forget about doing this and just reload, saving the state in the event of a pause or memory contention, and restarting the app as it were? Or should I figure out how I can re-architect my models so that I can pick and know which model I need to instantiate in this situation?

One thing I can imagine is having IDs in my models and storing them in the event of a pause and during resuming instantiating everything again, getting the ID of the last loaded model and opening the right view again.

This will take quite a lot of re-architecting, anyone done this before?

# ? Sep 15, 2015 05:23

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# ? May 17, 2024 10:22

Uziel: Jun 28, 2004; Ask me about losing 200lbs, and becoming the Viking God of W&W.

I have a few cases where I think async/await might improve user experience, but my coworker on the project doesn't think so. The project is legacy Web Forms. When the user clicks a button to save their work, we call a "Save" method on a business layer object and then notify the user that their save went through.

code:

protected void Save()
{
            Builder.Save();
            ExtNet.Msg.Notify("Builder Saved", "Builder has been commited to database").Show();
}

The Business Layer code essentially inserts the object into the DB, then takes that object and compiles it for the reporting database. The reporting database stuff takes 2 seconds, but ideally, we'd want the user to not be blocked during the report compile, and then notify them once it's complete.

code:

public void Save(bool compile = true)
{
         //serialization/database inserts

            if (compile)
                ReportCompiler.Compile(this);
        }

Is this a good case to use async/await? Or is there a better way?

# ? Sep 15, 2015 13:57

The Something Awful Forums > Discussion > Serious Hardware/Software Crap > The Cavern of COBOL > .NET Megathread 3.5: await GetGoodPosts()

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