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Why is it important to override GetHashCode when Equals method is overridden?
...kets. If the hash-code for two items does not match, they may never be considered equal (Equals will simply never be called).
The GetHashCode() method should reflect the Equals logic; the rules are:
if two things are equal (Equals(...) == true) then they must return the same value for GetHashCode...
With MySQL, how can I generate a column containing the record index in a table?
... @smhnaji MySQL requires that every "derived table" is given a name. I decided to call it "r" :) ... It has little purpose in this case, but you'd normally use it to reference attributes of the derived table, as if it was a real table.
– Daniel Vassallo
Feb 27...
Storyboard - refer to ViewController in AppDelegate
consider the following scenario: I have a storyboard-based app. I add a ViewController object to the storyboard, add the class files for this ViewController into the project and specify the name of the new class in the IB identity inspector. Now how am I going to refer to this ViewController program...
Run a callback only if an attribute has changed in Rails
...eRecord::Base
before_save :do_something, if: :will_save_change_to_status_id?
private
def do_something
# ...
end
end
The commit that changed ActiveRecord::Dirty is here: https://github.com/rails/rails/commit/16ae3db5a5c6a08383b974ae6c96faac5b4a3c81
Here is a blog post on these change...
Setting CSS pseudo-class rules from JavaScript
... can do it by altering the stylesheet, for example by adding the rule:
#elid:hover { background: red; }
assuming each element you want to affect has a unique ID to allow it to be selected.
In theory the document you want is http://www.w3.org/TR/DOM-Level-2-Style/Overview.html which means you can...
Can you create nested WITH clauses for Common Table Expressions?
... Stating that this is not nested, just because query 2 is not inside the parenthesis of query 1, sounds like a weak argument. I think it's nested (not recursively nested), because query 2 uses the result of query 1, which occurs with nesting too. Is defined that nesting can only be when a ...
convert ArrayList to JSONArray
...NArray(list);
References:
jsonarray constructor:
http://developer.android.com/reference/org/json/JSONArray.html#JSONArray%28java.util.Collection%29
collection:
http://developer.android.com/reference/java/util/Collection.html
...
Why is this jQuery click function not working?
...tion() {
$("#clicker").click(function () {
alert("Hello!");
$(".hide_div").hide();
});
});
As jQuery documentation states: "A page can't be manipulated safely until the document is "ready." jQuery detects this state of readiness for you. Code included inside $( document ).ready() will ...
How To Save Canvas As An Image With canvas.toDataURL()?
...
This works great... But in Android (Default browser in Galaxy S3) it just doesn't download the image, but i get the message "Downloading..." forever.
– Habrashat
Jul 28 '14 at 6:05
...
REST APIs: custom HTTP headers vs URL parameters
...aves true metadata about the request for custom headers.
HTTP has a very wide selection of headers that cover most everything you'll need. Where I've seen custom headers come up is in a system to system request operating on behalf of a user. The proxy system will validate the user and add "X-User...