Human-readable file size in C#
{
string[] units = { "B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
while(size >= 1024) {
size /= 1024;
++unit;
}
return String.Format("{0:0.#} {1}", size, units[unit]);
}
I made "bytes" a double so you could pass in fractions, which you might get when calculating download speeds (just add something like "/s" after the output).
A Simple Priority Queue in C#
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace QueueSpace
{
public class PriorityQueue<TValue> : PriorityQueue<TValue, int> { }
public class PriorityQueue<TValue, TPriority> where TPriority : IComparable
{
private SortedDictionary<TPriority, Queue<TValue>> dict = new SortedDictionary<TPriority, Queue<TValue>>();
public int Count { get; private set; }
public bool Empty { get { return Count == 0; } }
public void Enqueue(TValue val)
{
Enqueue(val, default(TPriority));
}
public void Enqueue(TValue val, TPriority pri)
{
++Count;
if (!dict.ContainsKey(pri)) dict[pri] = new Queue<TValue>();
dict[pri].Enqueue(val);
}
public TValue Dequeue()
{
--Count;
var item = dict.Last();
if (item.Value.Count == 1) dict.Remove(item.Key);
return item.Value.Dequeue();
}
}
class Program
{
static void Main(string[] args)
{
var pq = new PriorityQueue<int>();
for (int i = 0; i < 10; ++i)
{
pq.Enqueue(i,i/2);
}
while (!pq.Empty)
{
Console.Write(pq.Dequeue() + " ");
}
Console.ReadKey();
}
}
}
Output
Items with the same priority are dequeued in the same order that they were inserted.
Django Send HTML Emails
You can use this little function to load emails from a template and send them in both HTML and plaintext formats.
from django.template import loader, Context
from django.conf import settings
def send_multipart_email(subject, template, data_dict, recipient_list, from_email=settings.DEFAULT_FROM_EMAIL):
if type(recipient_list) != list: recipient_list = [recipient_list]
tt = loader.get_template(template+'.txt')
c = Context(data_dict)
e = EmailMultiAlternatives(subject, tt.render(c), from_email, recipient_list)
try:
ht = loader.get_template(template+'.html')
e.attach_alternative(ht.render(c), 'text/html')
except:
pass
e.send()
.NET Dock Panel
Apparently .NET does not come with any dock widget, like the ones used for the Toolbox and Properties window in Visual Studio. However, there is a freely available one on sourceforge called DockPanel Suite. Unfortunately, it seems to lack any sort of documentation!
This little code snippet below should be enough to get you started though. Just make sure you your form's IsMdiContainer property to True first.
InitializeComponent();
glControl.Load += new System.EventHandler(glControl_Load);
glControl.Paint += new System.Windows.Forms.PaintEventHandler(glControl_Paint);
glControl.Dock = DockStyle.Fill;
var dockPanel = new DockPanel();
dockPanel.Dock = DockStyle.Fill;
Controls.Add(dockPanel);
dockPanel.BringToFront();
var mainDock = new DockContent();
mainDock.ShowHint = DockState.Document;
mainDock.TabText = "untitled1";
mainDock.Controls.Add(glControl);
mainDock.Show(dockPanel);
var propGrid = new PropertyGrid();
propGrid.Dock = DockStyle.Fill;
var propertyDock = new DockContent();
propertyDock.Controls.Add(propGrid);
propertyDock.ShowHint = DockState.DockRight;
propertyDock.TabText = "Properties";
propertyDock.Show(dockPanel);
}
C# Blocking Queue
If you're writing a threaded application in C# and you need to wait until a resource becomes available, you can use this class. Very handy for producer/consumer scenarios.
{
Queue<T> que = new Queue<T>();
Semaphore sem = new Semaphore(0, Int32.MaxValue);
public void Enqueue(T item)
{
lock (que)
{
que.Enqueue(item);
}
sem.Release();
}
public T Dequeue()
{
sem.WaitOne();
lock (que)
{
return que.Dequeue();
}
}
}
Django, Flatpages, Markdown, and Syntax Highlighting
For what should have been an easy task, this turned out to be extraordinarily difficult.
I assume you have Django already installed. If not, the tutorials on djangoproject.com aren't too terrible, provided you're not on a shared server (that's another story!). I'm using Flatpages, but you can use whatever you want to follow along with this tutorial.
1. Install Markdown and Pygments for Python if you haven't already. If you're on Ubuntu, you can `sudo apt-get install python-markdown` or `easy_install Markdown` and `sudo apt-get install python-pygments`.
2. Go into your Django app and `mkdir templatetags`. This should be at the same level as `manage.py`, `settings.py` and `urls.py`. Then `cd` into that directory, and `touch __init__.py` (so that it becomes a module) and then add another file called something like `tags.py` (don't name it "markdown.py" -- that'll bite you later). Paste this code in there:
from django.template.defaultfilters import stringfilter
from django.conf import settings
register = template.Library()
@register.filter(name='markdown')
@stringfilter
def markdown(value, arg=''):
"""
Filter to create HTML out of Markdown, using custom extensions.
The diffrence between this filter and the django-internal markdown
filter (located in ``django/contrib/markup/templatetags/markup.py``)
is that this filter enables extensions to be load.
Usage::
{{ object.text|markdown }}
{{ object.text|markdown:"save" }}
{{ object.text|markdown:"codehilite" }}
{{ object.text|markdown:"save,codehilite" }}
This code is taken from
http://www.freewisdom.org/projects/python-markdown/Django
"""
try:
import markdown
except ImportError:
if settings.DEBUG:
raise (template.TemplateSyntaxError,
"Error in {% markdown %} filter: "
+ "The markdown library isn't installed.")
else :
from django.utils.html import escape, linebreaks
return linebreaks(escape(value))
else:
extensions=arg.split(",")
if len(extensions) > 0 and extensions[0] == "safe" :
extensions = extensions[1:]
safe_mode = True
else :
safe_mode = False
return markdown.markdown(value, extensions, safe_mode=safe_mode)
Yes, I'm leaving the link in there; I didn't write that code.
3. Go into `settings.py` and add your app to the `INSTALLED_APPS`. You actually have to `import` your own app too; this baffled me for about an hour. My app is called `tech_eval` so my `INSTALLED_APPS` looks like this:
INSTALLED_APPS = (
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.admin',
'django.contrib.flatpages',
'tech_eval',
)
4. Like I said, I'm using Flatpages, so my template looks like this (I saved it to djangoproject/app/templates/flatpages/default.html).
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<title>{{ flatpage.title }}</title>
<link rel="stylesheet" type="text/css" href="/tech_eval/media/css/code_style.css" />
</head>
<body>
<h1>{{ flatpage.title }}</h1>
{{ flatpage.content|markdown:"codehilite"|safe}}
</body>
</html>
Notice how we filter the content with markdown, make sure the codehilite extension is used, and flag it as `safe` afterwords (otherwise Django will automatically character-encode everything).
5. Hopefully this is already working for you at this point, but you probably want to add some color to your code. You can generate the appropriate css file with this:
Some different styles you can use (at least on my system) are:
(stolen from here).
Or just copy and paste this CSS file if you're lazy:
.codehilite .err { border: 1px solid #FF0000 } /* Error */
.codehilite .k { color: #008000; font-weight: bold } /* Keyword */
.codehilite .o { color: #666666 } /* Operator */
.codehilite .cm { color: #408080; font-style: italic } /* Comment.Multiline */
.codehilite .cp { color: #BC7A00 } /* Comment.Preproc */
.codehilite .c1 { color: #408080; font-style: italic } /* Comment.Single */
.codehilite .cs { color: #408080; font-style: italic } /* Comment.Special */
.codehilite .gd { color: #A00000 } /* Generic.Deleted */
.codehilite .ge { font-style: italic } /* Generic.Emph */
.codehilite .gr { color: #FF0000 } /* Generic.Error */
.codehilite .gh { color: #000080; font-weight: bold } /* Generic.Heading */
.codehilite .gi { color: #00A000 } /* Generic.Inserted */
.codehilite .go { color: #808080 } /* Generic.Output */
.codehilite .gp { color: #000080; font-weight: bold } /* Generic.Prompt */
.codehilite .gs { font-weight: bold } /* Generic.Strong */
.codehilite .gu { color: #800080; font-weight: bold } /* Generic.Subheading */
.codehilite .gt { color: #0040D0 } /* Generic.Traceback */
.codehilite .kc { color: #008000; font-weight: bold } /* Keyword.Constant */
.codehilite .kd { color: #008000; font-weight: bold } /* Keyword.Declaration */
.codehilite .kp { color: #008000 } /* Keyword.Pseudo */
.codehilite .kr { color: #008000; font-weight: bold } /* Keyword.Reserved */
.codehilite .kt { color: #B00040 } /* Keyword.Type */
.codehilite .m { color: #666666 } /* Literal.Number */
.codehilite .s { color: #BA2121 } /* Literal.String */
.codehilite .na { color: #7D9029 } /* Name.Attribute */
.codehilite .nb { color: #008000 } /* Name.Builtin */
.codehilite .nc { color: #0000FF; font-weight: bold } /* Name.Class */
.codehilite .no { color: #880000 } /* Name.Constant */
.codehilite .nd { color: #AA22FF } /* Name.Decorator */
.codehilite .ni { color: #999999; font-weight: bold } /* Name.Entity */
.codehilite .ne { color: #D2413A; font-weight: bold } /* Name.Exception */
.codehilite .nf { color: #0000FF } /* Name.Function */
.codehilite .nl { color: #A0A000 } /* Name.Label */
.codehilite .nn { color: #0000FF; font-weight: bold } /* Name.Namespace */
.codehilite .nt { color: #008000; font-weight: bold } /* Name.Tag */
.codehilite .nv { color: #19177C } /* Name.Variable */
.codehilite .ow { color: #AA22FF; font-weight: bold } /* Operator.Word */
.codehilite .w { color: #bbbbbb } /* Text.Whitespace */
.codehilite .mf { color: #666666 } /* Literal.Number.Float */
.codehilite .mh { color: #666666 } /* Literal.Number.Hex */
.codehilite .mi { color: #666666 } /* Literal.Number.Integer */
.codehilite .mo { color: #666666 } /* Literal.Number.Oct */
.codehilite .sb { color: #BA2121 } /* Literal.String.Backtick */
.codehilite .sc { color: #BA2121 } /* Literal.String.Char */
.codehilite .sd { color: #BA2121; font-style: italic } /* Literal.String.Doc */
.codehilite .s2 { color: #BA2121 } /* Literal.String.Double */
.codehilite .se { color: #BB6622; font-weight: bold } /* Literal.String.Escape */
.codehilite .sh { color: #BA2121 } /* Literal.String.Heredoc */
.codehilite .si { color: #BB6688; font-weight: bold } /* Literal.String.Interpol */
.codehilite .sx { color: #008000 } /* Literal.String.Other */
.codehilite .sr { color: #BB6688 } /* Literal.String.Regex */
.codehilite .s1 { color: #BA2121 } /* Literal.String.Single */
.codehilite .ss { color: #19177C } /* Literal.String.Symbol */
.codehilite .bp { color: #008000 } /* Name.Builtin.Pseudo */
.codehilite .vc { color: #19177C } /* Name.Variable.Class */
.codehilite .vg { color: #19177C } /* Name.Variable.Global */
.codehilite .vi { color: #19177C } /* Name.Variable.Instance */
.codehilite .il { color: #666666 } /* Literal.Number.Integer.Long */
.codehilitetable { border: 1px solid #666; width: 100%; background-color: #666; }
.codehilitetable .linenos { background-color: #666; padding: 0 5px; width: 20px; }
.codehilitetable .code { padding: 0 15px; background-color: #fff; }
And that should pretty much be it. Let me know if I missed anything or this was too difficult to follow along.
Qt + OpenGL Code Example
I wanted to develop a game using OpenGL but I was having trouble deciding on a windowing library. Somebody suggested I try Qt, so I decided to give it another shot. I heard it was good, but the editor it came with was so foreign and unintuitive. Unfortunately, this overshadowed what a beautiful library Qt really is! It takes a little getting used to, but it really is well designed.
array_map_recursive
Not much needs to be said here.
$ret = array();
foreach($arr as $key => $val) {
if(is_array($val)) $ret[$key] = array_map_recursive($callback, $val);
else $ret[$key] = $callback($val);
}
return $ret;
}
I wrote this so that I could do this...
foreach($filters as $filter) $view_vars = array_map_recursive($filter, $view_vars);
Which just sanitizes my variables before I print them.
All I want is a drag-and-drop CD burner
I know I've mostly been posting code snippets here, but I originally started this site to post more in-depth tutorials. This isn't going to be one of those. I'm taking a spin and would like to say a few words on the design of good software -- the second half of this site that's been neglected.
My brother's girlfriend asked me to burn some files for her using her laptop the other day, so I tried. I didn't think it would be so difficult.
So I popped in the blank disc, and iTunes came up, exclaiming that it could burn stuff for me. Fine, I'll try that. It told me I had to create a new playlist (Why? I'm just going to delete it in 5 seconds). So I did. And then I tried to drag and drop my videos onto the playlist. Nothing. Okay. Let's dig through the menus: "Add to playlist"? No. "Import files"? No. It looks to me like I have to add the files to my library, then search for those files that I just added, figure out how to add them to my newly created playlist, burn them, and then delete the playlist I didn't want in the first place. Brilliant. Except I couldn't figure that out, and I still haven't the faintest idea how to use iTunes. Call me idiot, iTune-lovers, but software really shouldn't take more than about 3 minutes to figure out how to do what you want with it.
Next I tried ImgBurn, something a friend recommended to me, which was indeed great for burning images, as the name suggests, but pretty horrid at burning a list of files. Fail.
I eventually just went into "My Computer" and dragged some files on it. Windows told me I had to format the CD (it was rewriteable) first. Fine. That took an extraordinarily long time, and then finally when it started burning it told me it would be finished in 0 seconds, but it literally took between thirty minutes and an hour. I know her drive isn't that slow, it's a new computer.
CDBurnerXP has worked great in the past for me, but apparently it's a failure on Windows 7. The "used space" bar was just plain wrong, and when I tried telling it that it was an idiot, it threw a fit and crashed.
Nero was good, back in the day, until they figured out they were getting popular and thought they could get away with adding whatever crapware they wanted. Now I just refuse to support their bullshit.
All I wanted to do was to drag-and-drop some files onto a program window, list them for me, and tell me how much space I've got left. Click burn, and that's it. Don't touch my files, don't convert them, don't move, copy, sort, cache or archive them. Don't install useless crap on my computer, and don't have me six thousand features I don't need.
Give me what I want. Make it big, bold, obvious, easy to find. And make it do what it's supposed to do when I click it. No more, no less. Is that so hard? Why can't people develop nice, clean, simple, intuitive UIs? We're not asking you to invent anything new, just take what's already been done, and works, and use that. There's frameworks for it. Use them!
jQuery Select Table Column or Row
Table rows are pretty easy to work as all the td elements are contained within one tr, but how would you grab all the tds in a single column? Why, by using these selectors of course!
return $('tr:nth-child('+(i+1)+') td', this);
}
$.fn.column = function(i) {
return $('tr td:nth-child('+(i+1)+')', this);
}
// example - this will make the first column of every table red
$(document).ready(function() {
$('table').column(0).css('background-color','red');
});
I like my selectors zero-based, but you can get rid of the +1 if you don't like it.