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Rails 3 check if attribute changed
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Check out ActiveModel::Dirty (available on all models by default). The documentation is really good, but it lets you do things such as:
@user.street1_changed? # => true/false
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What are the differences between Abstract Factory and Factory design patterns?
...le the desired object
instantiation.
The quote assumes that an object is calling its own factory method here. Therefore the only thing that could change the return value would be a subclass.
The abstract factory is an object that has multiple factory methods on it. Looking at the first half of your...
Pointers vs. values in parameters and return values
... function values, and interface values are implemented with pointers internally, and a pointer to them is often redundant.
Elsewhere, use pointers for big structs or structs you'll have to change, and otherwise pass values, because getting things changed by surprise via a pointer is confusing.
O...
Yes/No message box using QMessageBox
...ult button with an extra argument (Qt "chooses a suitable default automatically" if you don't or specify QMessageBox::NoButton).
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Are there any side effects of returning from inside a using() statement?
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No, I think it's clearer this way. Don't worry, Dispose will still be called "on the way out" - and only after the return value is fully evaluated. If an exception is thrown at any point (including evaluating the return value) Dispose will still be called too.
While you certainly could take the...
A variable modified inside a while loop is not remembered
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@AvinashYadav The problem isn't really related to while loop or for loop; rather the use of subshell i.e., in cmd1 | cmd2, cmd2 is in a subshell. So if a for loop is executed in a subshell, the unexpected/problematic behaviour will be exhibited.
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What is the best Distributed Brute Force countermeasure?
...so far I'm winning (so to speak). But I've run into a pretty non-trivial challenge (one that most auth libraries miss entirely, but I insist on handling it properly): how to deal intelligently with large-scale, distributed, variable-username brute-force attacks .
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SQL Server - transactions roll back on error?
...xact_abort on before your transaction to make sure sql rolls back automatically in case of error.
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How to convert Hexadecimal #FFFFFF to System.Drawing.Color [duplicate]
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string hex = "#FFFFFF";
Color _color = System.Drawing.ColorTranslator.FromHtml(hex);
Note: the hash is important!
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MFC Dialog中嵌入View、动态创建View的方法 - C/C++ - 清泛网 - 专注C/C++及内核技术
...的需要手动调一下。代码如下，亲测有效：
//.h
CView *m_pDemoView;
//.cpp 构造函数或OnInitDialog函数
CMainContainer::OnInitDialog() //CDialog才有，像CWnd等没有OnInitDialog可以放在构造函数中，然后OnPaint()函数中改变大小并显示。
{
m_pDem...