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How to rollback a specific migration?
...nt to go back.
For example:
rake db:rollback STEP=5
Will also rollback all the migration that happened later (4, 3, 2 and also 1).
To roll back all migrations back to (and including) a target migration, use: (This corrected command was added AFTER all the comments pointing out the error in the ...
Objective-C: Property / instance variable in category
...e, it wouldn't work.
Fortunately, the Objective-C runtime has this thing called Associated Objects that can do exactly what you're wanting:
#import <objc/runtime.h>
static void *MyClassResultKey;
@implementation MyClass
- (NSString *)test {
NSString *result = objc_getAssociatedObject(sel...
Where is array's length property defined?
...uage itself.
10.7. Array Members
The members of an array type are all of the following:
The public final field length, which contains the number of components of the array. length may be positive or zero.
The public method clone, which overrides the method of the same name in clas...
Why do x86-64 systems have only a 48 bit virtual address space?
...
Because that's all that's needed. 48 bits give you an address space of 256 terabyte. That's a lot. You're not going to see a system which needs more than that any time soon.
So CPU manufacturers took a shortcut. They use an instruction set...
Why would I use Scala/Lift over Java/Spring? [closed]
...over it. From my perspective and experience, Java Annotations and Spring really minimizes the amount of coding that you have to do for an application. Does Scala/Lift improve upon that?
...
Return None if Dictionary key is not available
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answered May 25 '11 at 20:52
Tim PietzckerTim Pietzcker
283k5353 gold badges435435 silver badges508508 bronze badges
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How to read/write from/to file using Go?
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Let's make a Go 1-compatible list of all the ways to read and write files in Go.
Because file API has changed recently and most other answers don't work with Go 1. They also miss bufio which is important IMHO.
In the following examples I copy a file by reading...
Hide keyboard when scroll UITableView
...
420
Here is the cleanest way to achieve this in iOS 7.0 and above:
tableView.keyboardDismissMode =...
How to replace multiple strings in a file using PowerShell
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answered Aug 4 '10 at 7:20
George HowarthGeorge Howarth
2,3811515 silver badges1717 bronze badges
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Automatically capture output of last command into a variable using Bash?
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This is a really hacky solution, but it seems to mostly work some of the time. During testing, I noted it sometimes didn't work very well when getting a ^C on the command line, though I did tweak it a bit to behave a bit better.
This...