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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...
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...
C++特化模板函数的符号多重定义错误问题 - C/C++ - 清泛网 - 专注C/C++及内核技术
C++特化模板函数的符号多重定义错误问题error LNK2005: "void __stdcall SerializeElements<class CLogEvent> ...fatal error LNK1169: 找到一个或多个多重定义的符号.我...特化模板函数SerializeElements时，报重复定义的错误，如下：
error LNK2005: "void __std...
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
...
Checking for a dirty index or untracked files with Git
...din, command line options, arguments, etc. will produce the same output in all versions of Git where the command/option exists). New output variations in plumbing commands can be introduced via new options, but that can not introduce any problems for programs that have already been written against o...
Guaranteed lifetime of temporary in C++?
...or the lifetime of a temporary variable that is created within a function call but not used as a parameter? Here's an example class:
...
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...
How to perform case-insensitive sorting in JavaScript?
... Do mind that localeCompare's advanced options are not yet supported on all platforms/browsers. I know they are not used in this example, but just wanted to add for clarity. See MDN for more info
– Ayame__
Jan 9 '14 at 15:05
...
What is the easiest way to push an element to the beginning of the array?
...the top of the page could be better formatted, it is very difficult to visually scan as it is. I found it because I knew the method name I was looking for :)
– mu is too short
May 22 '11 at 6:45
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Any way to write a Windows .bat file to kill processes? [closed]
...out of my IDE. Yes, these are processes from programs that my company installs on my machine for security and compliance. What I'd like to do is have a .bat file or script of some kind with which I can kill the processes in question.
...