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How to get the original value of an attribute in Rails
...flow.com/a/50973808/9359123
Appending _was is deprecated in rails 5.1, now you should append _before_last_save
Something like:
before_save object
do_something_with object.name_before_last_save
end
Will return the name value before your last save at database (works for save and create)
The...
How can I swap positions of two open files (in splits) in vim?
..._|______|
| three |
| |
|__________________|
Now make either 'one' or 'two' the active window, then issue the command ctrl+w r. This 'rotates' the windows in the current row, leaving you with:
____________________
| two | one |
| | |
|___________|...
How to install both Python 2.x and Python 3.x in Windows
I do most of my programming in Python 3.x on Windows 7, but now I need to use the Python Imaging Library (PIL), ImageMagick, and wxPython, all of which require Python 2.x.
...
What is a segmentation fault?
...nd introducing hard-to-debug memory bugs. Whenever you get a segfault you know you are doing something wrong with memory – accessing variable that has already been freed, writing to a read-only portion of the memory, etc. Segmentation fault is essentially the same in most languages that let you me...
Pass in an array of Deferreds to $.when()
....my_array).then( ___ );
In either case, since it's unlikely that you'll known in advance how many formal parameters the .then handler will require, that handler would need to process the arguments array in order to retrieve the result of each promise.
...
call a static method inside a class?
...o the most common way of calling a static method:
self::staticMethod();
Now, before you start thinking that the :: is the static call operator, let me give you another example:
self::bar();
This will print baz = 1, which means that $this->bar() and self::bar() do exactly the same thing; tha...
Git fetch remote branch
...ess for me, it created a local branch named origin/<branch> which is now ambiguous to the remote branch origin/<branch> and I don't know how to get rid of the crazy local branch!
– Alan Moore
Jul 9 '15 at 17:00
...
How do API Keys and Secret Keys work? Would it be secure if I have to pass my API and secret keys to
...the result is greater than ten, subtracts ten. So f(2) = 5, f(8) = 1, etc. Now, we can make another function, call it f', that goes backwards, by adding seven instead of three. f'(5) = 2, f'(1) = 8, etc.
That's an example of a two-way function and its inverse. Theoretically, any mathematical functi...
In PowerShell, how do I define a function in a file and call it from the PowerShell commandline?
... your functions in it to MyFunctions.psm1 (you've just created a module!). Now for a module to load properly, you have to do some specific things with the file. First for Import-Module to see the module (you use this cmdlet to load the module into the shell), it has to be in a specific location. The...
Advantages of stateless programming?
...
True, I should acknowledge that probably a lot of my positive experience with F# has more to do with F# than it does with functional programming. But still, there is a strong correlation between the two, and even though things like type infere...