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C# pattern to prevent an event handler hooked twice [duplicate]
... need to check for null:
using System.Linq; // Required for the .Contains call below:
...
private EventHandler foo;
public event EventHandler Foo
{
add
{
if (foo == null || !foo.GetInvocationList().Contains(value))
{
foo += value;
}
}
remove
...
ReactJS: Modeling Bi-Directional Infinite Scrolling
...nite-scroller/
You can check out the source code for the logic, but I basically followed the recipe @Vjeux outlined in the above answer. I haven't yet tackled jumping to a particular item, but I'm hoping to implement that soon.
Here's the nitty-gritty of what the code currently looks like:
var Re...
iPhone hide Navigation Bar only on first page
...s hidden when the first view loads and then hidden when the "children" get called. Trouble is that I cannot find the event/action to trigger it to hide again when they get back to the root view....
...
How to declare an array in Python?
...e should never refer to anything other than a list", since Python is dynamically typed.
*The default built-in Python type is called a list, not an array. It is an ordered container of arbitrary length that can hold a heterogenous collection of objects (their types do not matter and can be freely ...
Access-Control-Allow-Origin error sending a jQuery Post to Google API's
... moment jQuery sees the URL belongs to a different domain, it assumes that call as a cross domain call, thus crossdomain:true is not required here.
Also, important to note that you cannot make a synchronous call with $.ajax if your URL belongs to a different domain (cross domain) or you are using J...
How to determine total number of open/active connections in ms sql server 2005
...
This shows the number of connections per each DB:
SELECT
DB_NAME(dbid) as DBName,
COUNT(dbid) as NumberOfConnections,
loginame as LoginName
FROM
sys.sysprocesses
WHERE
dbid > 0
GROUP BY
dbid, loginame
And this gives the total:
SELECT
COUNT(dbid) as TotalConn...
How to ensure a form field is submitted when it is disabled?
...t;select disabled="disabled">
....
</select>
<input type="hidden" name="select_name" value="selected value" />
Where select_name is the name that you would normally give the <select>.
Another option.
<select name="myselect" disabled="disabled">
<option value...
How to upgrade all Python packages with pip?
...s and FIXME errors.
For pip < 10.0.1
import pip
from subprocess import call
packages = [dist.project_name for dist in pip.get_installed_distributions()]
call("pip install --upgrade " + ' '.join(packages), shell=True)
For pip >= 10.0.1
import pkg_resources
from subprocess import call
pack...
How to get URL parameter using jQuery or plain JavaScript?
...Thanks! But when copying this, I found a nasty surprise, involving a zero-width whitespace (\u200b) towards the end there. Making the script have an invisible syntax error.
– Christofer Ohlsson
Aug 12 '14 at 8:54
...
Code Golf: Collatz Conjecture
...esp+0x04], 2
jne .usage
mov ebx, [esp+0x08]
push dword [ebx+0x04]
call atoi
add esp, 4
cmp eax, 0
je .usage
mov ebx, eax
push eax
push msg
.loop:
mov [esp+0x04], ebx
call printf
test ebx, 0x01
jz .even
.odd:
lea ebx, [1+ebx*2+ebx]
jmp .loop
.even:
shr ebx, 1...