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Why are #ifndef and #define used in C++ header files?
...his case HEADERFILE_H) is defined. Then if it's not defined, it defines it and continues to the rest of the page.
When the code is included again, the first ifndef fails, resulting in a blank file.
That prevents double declaration of any identifiers such as types, enums and static variables.
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How do I check if an object has a specific property in JavaScript?
...king for. If you want to know if an object physically contains a property (and it is not coming from somewhere up on the prototype chain) then object.hasOwnProperty is the way to go. All modern browsers support it. (It was missing in older versions of Safari - 2.0.1 and older - but those versions of...
Getting the SQL from a Django QuerySet [duplicate]
...use "Django never actually interpolates the parameters: it sends the query and the parameters separately to the database adapter, which performs the appropriate operations." Source: code.djangoproject.com/ticket/17741
– gregoltsov
Jul 7 '14 at 14:50
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How update the _id of one MongoDB Document?
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You cannot update it. You'll have to save the document using a new _id, and then remove the old document.
// store the document in a variable
doc = db.clients.findOne({_id: ObjectId("4cc45467c55f4d2d2a000002")})
// set a new _id on the document
doc._id = ObjectId("4c8a331bda76c559ef000004")
//...
How to sort two lists (which reference each other) in the exact same way
...rt(); zip(*tups)
100000 loops, best of 3: 2.84 us per loop
On the other hand, for larger lists, the one-line version could be faster:
>>> %timeit zip(*sorted(zip(list1, list2)))
100 loops, best of 3: 8.09 ms per loop
>>> %timeit tups = zip(list1, list2); tups.sort(); zip(*tups)
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Split Python Flask app into multiple files
I'm having trouble understanding how to split a flask app into multiple files.
4 Answers
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How to pick just one item from a generator?
...__() in py3k. The builtin next(iterator) has been around since Python 2.6, and is what should be used in all new Python code, and it's trivial to backimplement if you need to support py <= 2.5.
– Jonathan Baldwin
Apr 10 '14 at 19:58
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Ruby: require vs require_relative - best practice to workaround running in both Ruby =1.
What is the best practice if I want to require a relative file in Ruby and I want it to work in both 1.8.x and >=1.9.2?
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How to get current route in Symfony 2?
...') is not reliable because it is for debug purpose only (symfony dev said) and does not work if request is forwarded... see supernova's answer which are documented and are more fail-safe
– luiges90
Nov 14 '12 at 2:38
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How do I add a placeholder on a CharField in Django?
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This was the easiest method for me - and it was nice that all the other attributes (i.e. required) were still automatically added without me having to specify them.
– JxAxMxIxN
Jun 25 '17 at 17:17
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