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Run a callback only if an attribute has changed in Rails
...
Rails 5.1+
class Page < ActiveRecord::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/16ae3db5a5c6a08383b974ae...
Can Objective-C switch on NSString?
... @abbood For more information about enum, see the posting NS_ENUM & NS_OPTIONS by Mattt Thompson.
– Basil Bourque
Oct 21 '13 at 21:32
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How to get the first column of a pandas DataFrame as a Series?
...c wasn't there yet back then. In 2016, the correct answer is Jeff's (after all he's pandas God, mind you ;-)). I'm not sure what's SO's policy regarding update of answers due to API change; I'm honestly surprised by the number of votes for this answer, didn't think it was that useful to people...
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How to Remove ReadOnly Attribute on File Using PowerShell?
...e here? As for Keith's answer, he's using PSCX. Not everyone has those installed and that's not really a case of PowerShell v1 vs. v2.
– Joey
Apr 22 '11 at 9:28
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What are the differences between a multidimensional array and an array of arrays in C#?
...t32 'value') cil managed
{
// Code size 7 (0x7)
.maxstack 8
IL_0000: ldarg.0
IL_0001: ldarg.1
IL_0002: ldelem.ref
IL_0003: ldarg.2
IL_0004: ldarg.3
IL_0005: stelem.i4
IL_0006: ret
} // end of method Program::SetElementAt
.method private hidebysig static void SetElem...
Generate JSON string from NSDictionary in iOS
...ke easier to read).
@interface NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint;
@end
.
@implementation NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint {
NSError *error;
NSData *jsonData = [NSJSONSerial...
Why do people put code like “throw 1; ” and “for(;;);” in front of json responses? [du
...ruct, they'll be the attacker's own versions of those objects, with potentially-unexpected behaviour.
For example, you can hack a setter-property into Object, that would betray the values written in object literals:
Object.prototype.__defineSetter__('x', function(x) {
alert('Ha! I steal '+x);
...
Vertical (rotated) label in Android
...d simple vertical text implementation, extending TextView. This means that all standard styles of TextView may be used, because it is extended TextView.
public class VerticalTextView extends TextView{
final boolean topDown;
public VerticalTextView(Context context, AttributeSet attrs){
...
Multi-line regex support in Vim
...t of other differences between Vim and Perl regexes.
Instead you can use \_., which means "match any single character including newline". It's a bit shorter than what you have. See :h /\_..
/This\_.*text/
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NSRange to Range
...dited Jan 4 '17 at 14:30
juancazalla
9461010 silver badges1616 bronze badges
answered Oct 22 '14 at 21:46
Alex...