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How do you write a migration to rename an ActiveRecord model and its table in Rails?
...y.
Edit:
In Rails 3.1 & 4, ActiveRecord::Migration::CommandRecorder knows how to reverse rename_table migrations, so you can do this:
class RenameOldTableToNewTable < ActiveRecord::Migration
def change
rename_table :old_table_name, :new_table_name
end
end
(You still have to go t...
Why is IoC / DI not common in Python?
...Python, I simply import from a different location using the same name. But now I am thinking if it's also possible the other way round by defining a MyClassInstances class to each MyClass in Java, which contains only static, fully initialized instances. That would be wired :D
–...
How are 3D games so efficient? [closed]
...
Eeeeek!
I know that this question is old, but its exciting that no one has mentioned VSync!!!???
You compared the CPU usage of the game at 60fps to CPU usage of the teapot demo at 60fps.
Isn't it apparent, that both run (more or less)...
How to redirect cin and cout to files?
...
Here is an working example of what you want to do. Read the comments to know what each line in the code does. I've tested it on my pc with gcc 4.6.1; it works fine.
#include <iostream>
#include <fstream>
#include <string>
void f()
{
std::string line;
while(std::getline(...
Foreign Key to non-primary key
... key, otherwise, data-garbage is the result sooner rather than later...
Now what you can do in this case (short of rewritting the entire application) is inserting a CHECK-constraint, with a scalar function checking the presence of the key:
IF EXISTS (SELECT * FROM sys.check_constraints WHERE ob...
What is an IndexOutOfRangeException / ArgumentOutOfRangeException and how do I fix it?
... (nullables has been introduced with .NET 2.0 and anyway it's also a well-known convention in use from many years) if they didn't find anything. Let's imagine you have an array of objects comparable with a string. You may think to write this code:
// Items comparable with a string
Console.WriteLine...
Why do we need tuples in Python (or any immutable data type)?
...ding a tuple is over 7.6 times faster than building the equivalent list -- now you can't say you've "never seen a noticeable difference" any more, unless your definition of "noticeable" is truly peculiar...
– Alex Martelli
Feb 1 '10 at 4:35
...
Instance variables vs. class variables in Python
...else it's code created by an aberrant programmer wanting to show off they know some obscure corner of Python programming.
Alex mentions in his reply that access will be (a little bit) faster due to one less level of lookup... let me further clarify for those who don't know about how this works yet....
How do I catch a numpy warning like it's an exception (not just for testing)?
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To add a little to @Bakuriu's answer:
If you already know where the warning is likely to occur then it's often cleaner to use the numpy.errstate context manager, rather than numpy.seterr which treats all subsequent warnings of the same type the same regardless of where they occ...
How to add a custom right-click menu to a webpage?
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@Shashwat You know place, where user has clicked, and you don't have original menu. Create a container in that place and display your menu there.
– Radek Benkel
Sep 18 '12 at 14:32
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