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Extracting bits with a single multiplication
...d-add operations. The key is to allow overflow to "shift away" the bits we don't need and put the ones we want in the right place.
Multiplication by 4 (00000100) would shift everything left by 2 and get you to a00b0000 . To get the b to move up we need to multiply by 1 (to keep the a in the right ...
When to use a “has_many :through” relation in Rails?
...r and Group.
If you wanted to have users belong to groups, then you could do something like this:
class Group < ActiveRecord::Base
has_many :users
end
class User < ActiveRecord::Base
belongs_to :group
end
What if you wanted to track additional metadata around the association? For exa...
Convert pandas timezone-aware DateTimeIndex to naive timestamp, but in certain timezone
...lize to make a Timestamp or DateTimeIndex timezone aware, but how can you do the opposite: how can you convert a timezone aware Timestamp to a naive one, while preserving its timezone?
...
Measuring text height to be drawn on Canvas ( Android )
Any straight forward way to measure the height of text?
The way I am doing it now is by using Paint's measureText() to get the width, then by trial and error finding a value to get an approximate height. I've also been messing around with FontMetrics , but all these seem like approximate methods ...
Take a full page screenshot with Firefox on the command-line
I'm running Firefox on a Xvfb in a VPS. What I want to do is to take a full page screenshot of the page.
6 Answers
...
How to save an HTML5 Canvas as an image on a server?
... width="578" height="200"></canvas>
<script>
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
// begin custom shape
context.beginPath();
context.moveTo(170, 80);
context.bezierCurveTo(130, 100, 130, 150, 230, 150);
context.bezierC...
How to bind RadioButtons to an enum?
...
From what I can tell, this must be done unless the radio buttons are in different groups (and AFAIK buttons without GroupName set that have the same parent are by default in the same group). Otherwise, the calls to set the property "bounce" and result in odd b...
Why should I care about lightweight vs. annotated tags?
...e that v1.7.4 has been tagged (declared ready) and you're not so sure, who do you talk to? The person whose name is in the annotated tag! (If you live in a distrustful world, this also keeps people from getting away with tagging things they shouldn't.) If you're a consumer, that name is a stamp of a...
How to check if click event is already bound - JQuery
... with jQuery._data(elem, 'events'), an internal data structure, which is undocumented and therefore not 100% guaranteed to remain stable. This shouldn't, however, be a problem, and the relevant line of the plugin code above can be changed to the following:
var data = jQuery._data(this[0], 'events'...
Java switch statement: Constant expression required, but it IS constant
...) and definite assignment (§16).
In your example, the Foo.BA* variables do not have initializers, and hence do not qualify as "constant variables". The fix is simple; change the Foo.BA* variable declarations to have initializers that are compile-time constant expressions.
In other examples (whe...