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How to return smart pointers (shared_ptr), by reference or by value?
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Return smart pointers by value.
As you've said, if you return it by reference, you won't properly increment the reference count, which opens up the risk of deleting something at the improper time. That alone should be enough reason to not return ...
@Resource vs @Autowired
...th, without specifying any attributes of the annotation, perform injection by type. The difference is:
@Resource allows you to specify a name of the injected bean
@Autowired allows you to mark it as non-mandatory.
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Mean per group in a data.frame [duplicate]
...667 54.00000
Here we aggregate columns 3 and 4 of data.frame d, grouping by d$Name, and applying the mean function.
Or, using a formula interface:
aggregate(. ~ Name, d[-2], mean)
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Test if element is present using Selenium WebDriver?
...nt is present, you could try this
Boolean isPresent = driver.findElements(By.yourLocator).size() > 0
This will return true if at least one element is found and false if it does not exist.
The official documentation recommends this method:
findElement should not be used to look for non-pre...
Why does C++11's lambda require “mutable” keyword for capture-by-value, by default?
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It requires mutable because by default, a function object should produce the same result every time it's called. This is the difference between an object orientated function and a function using a global variable, effectively.
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find() with nil when there are no records
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Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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how to remove X-Powered-By in ExpressJS [duplicate]
I want to remove X-Powered-By for Security,Save Bandwidth in ExpressJS(node.js). how to do it?
it could be filter(app.use) ?
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Passing Objects By Reference or Value in C#
In C#, I have always thought that non-primitive variables were passed by reference and primitive values passed by value.
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Swift: Pass array by reference?
...nt to pass my Swift Array account.chats to chatsViewController.chats by reference (so that when I add a chat to account.chats , chatsViewController.chats still points to account.chats ). I.e., I don't want Swift to separate the two arrays when the length of account.chats changes.
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ng-repeat :filter by single field
...ter page. Use an object, and set the color in the color property:
Search by color: <input type="text" ng-model="search.color">
<div ng-repeat="product in products | filter:search">
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