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What does “hashable” mean in Python?
...ue which never changes during its lifetime (it needs a __hash__() method), and can be compared to other objects (it needs an __eq__() or __cmp__() method). Hashable objects which compare equal must have the same hash value.
Hashability makes an object usable as a dictionary key and a set member...
How many GCC optimization levels are there?
...e even more)
-Ofast (optimize very aggressively to the point of breaking standard compliance)
-Og (Optimize debugging experience. -Og enables optimizations that do not interfere with debugging. It should be the
optimization level of choice for the standard edit-compile-debug cycle, offeri...
How to print number with commas as thousands separators?
I am trying to print an integer in Python 2.6.1 with commas as thousands separators. For example, I want to show the number 1234567 as 1,234,567 . How would I go about doing this? I have seen many examples on Google, but I am looking for the simplest practical way.
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How can I declare and use Boolean variables in a shell script?
...s before the revision on Feb 12, 2014 pertain only to the original answer, and many of the comments are wrong when associated with the revised answer. For example, Dennis Williamson's comment about bash builtin true on Jun 2, 2010 only applies to the original answer, not the revised.
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Finding all possible combinations of numbers to reach a given sum
...])=15
This type of algorithms are very well explained in the following Standford's Abstract Programming lecture - this video is very recommendable to understand how recursion works to generate permutations of solutions.
Edit
The above as a generator function, making it a bit more useful. Require...
Why do access tokens expire?
I am just getting started working with Google API and OAuth2. When the client authorizes my app I am given a "refresh token" and a short lived "access token". Now every time the access token expires, I can POST my refresh token to Google and they will give me a new access token.
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iPhone Safari Web App opens links in new window
...is launched from Home Screen, all links will open in new window in Safari (and lose full screen functionality). How can I prevent it? I couldn't find any help, only the same unanswered question.
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How to detect my browser version and operating system using JavaScript?
I have tried using the code below but it only display results in Chrome and Mozilla not working in IE6.
10 Answers
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Run php script as daemon process
I need to run a php script as daemon process (wait for instructions and do stuff). cron job will not do it for me because actions need to be taken as soon as instruction arrives. I know PHP is not really the best option for daemon processes due to memory management issues, but due to various reasons...
How do I clone a Django model instance object and save it to the database?
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Just change the primary key of your object and run save().
obj = Foo.objects.get(pk=<some_existing_pk>)
obj.pk = None
obj.save()
If you want auto-generated key, set the new key to None.
More on UPDATE/INSERT here.
Official docs on copying model instances: h...