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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...
UIGestureRecognizer on UIImageView
...nEnabled = YES;
UIPinchGestureRecognizer *pgr = [[UIPinchGestureRecognizer alloc]
initWithTarget:self action:@selector(handlePinch:)];
pgr.delegate = self;
[imageView addGestureRecognizer:pgr];
[pgr release];
:
:
- (void)handlePinch:(UIPinchGestureRecognizer *)pinchGestureRecognizer
{
//handl...
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
...
href image link download on click
...t, it's a good thing to know. Although you need modernizr, I now use it in all my projects so... I'll accept your answer as the new answer
– Pierre
May 1 '13 at 12:05
1
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@ variables in Ruby on Rails
...cope (current block)
@title is an instance variable - and is available to all methods within the class.
You can read more here:
http://strugglingwithruby.blogspot.dk/2010/03/variables.html
In Ruby on Rails - declaring your variables in your controller as instance variables (@title) makes them ava...
Getting current device language in iOS?
...
The solutions provided will actually return the current region of the device - not the currently selected language. These are often one and the same. However, if I am in North America and I set my language to Japanese, my region will still be English (Unite...
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...
Using Git, how could I search for a string across all branches?
Using Git, how could I search within all files in all local branches for a given string?
5 Answers
...
Unsubscribe anonymous method in C#
...ered Oct 8 '08 at 15:33
Jacob KrallJacob Krall
24.8k66 gold badges5757 silver badges7373 bronze badges
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