Yesterday I was at the Dutch Windows Phone 7 LAN party, "and all I got was this damn T-shirt." ;-)
It was a great day, in which the Dutch Windows Phone 7 developer community tried to come together with dozens of developers/designers to create a WP7 app from scratch. For some more information (including some killer images), please check out my description in Dutch or the English machine-translation made possible by a Google server farm.
After recently changing the look of my blog not only did I lose my Google Analytics code from the template, but also the inclusion of Syntax Highlighter. I added analytics back earlier, but hadn't come round to putting source highlighting back into place. This has now been done, and all source code posted while highlighting was gone now has the needed brush class in place again. Hopefully this will make you enjoy reading code on this weblog even better.
I've received some positive reactions to my previous post, in which I gave source code of a lazy implementation of a SplitUp() function that could be used for paging an IEnumerable<T>.
However, I also got comments that example code on how you could use this would be nice. I had been thinking about that - also to show off exactly how the SplitUp() code is lazy and what actually happens if you use it - but decided to leave it out. That was mainly because I myself already knew; it just wasn't a goal of that previous blog post for me. Personally I'm not that much of a "need to see it work in an example" kind of guy, you know? Plus, blog posts take a bit of time. ;-)
Having said that, I can now give you this example, which should be self-explanatory if you run the following code in a console app project that includes the source from the previous blog code as well. Hope you enjoy it; as always all comments are welcome!
namespace SplitUpExample
{
using System;
using System.Linq;
using System.Collections.Generic;
using peSHIr.Utilities;
class Program
{
static bool TraceDataCreation;
static Action<string> println = text => Console.WriteLine(text);
static Action<string> print = text => Console.Write(text);
static Action newline = () => Console.WriteLine();
static void Main(string[] args)
{
newline();
println("* How can SplitUp() be used for paging");
TraceDataCreation = false;
var allData = TestData(64);
var pagedData = allData.SplitUp(7);
foreach (var page in pagedData)
{
print("Page:");
foreach (int i in page)
{
print(" ");
print(i.ToString());
}
newline();
}
newline();
println("* And is it really lazy?");
TraceDataCreation = true;
println("Calling SplitUp() on infinite sequence now");
var pagedInfinity = TestData().SplitUp(4);
println("Retrieving first page now");
var page1 = pagedInfinity.ElementAt(0);
println("Retrieving third page now");
var page3 = pagedInfinity.ElementAt(2);
Action<string,int,int> results = (text,sum,count)
=> Console.WriteLine("{0}: {1}, {2}", text, sum, count);
println("Showing results:");
results("First page", page1.Sum(), page1.Count());
results("Third page", page3.Sum(), page3.Count());
println("So yes, SplitUp() is lazy like LINQ! ;-)");
#if DEBUG
newline();
println("(Key to quit)");
Console.ReadKey();
#endif
}
static IEnumerable<int> TestData(int n)
{
return TestData().Take(n);
}
static IEnumerable<int> TestData()
{
// WARNING: this returns an infinite sequence!
// Or at least: until int overflows... ;-)
int i = 0;
while (true)
{
if (TraceDataCreation)
Console.WriteLine("Yielding {0}", i);
yield return i++;
}
}
}
}