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Explaining Python's '__enter__' and '__exit__'

I saw this in someone's code. What does it mean? 6 Answers 6 ...
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C# 'is' operator performance

... @mcmillab: I will guarantee that whatever you're doing, you'll have bottlenecks many orders of magnitude larger than any performance degradation the is operator is causing you, and that the over heard of designing & coding around the is operator will cos...
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Java: difference between strong/soft/weak/phantom reference

... strong reference), then even if a new customer comes in the restaurant or what so ever happnes, you will never leave your table (the memory area on heap). The waiter has no right to tell you (or even request you) to leave the restaurant. If you are a soft customer (analogous to soft reference), the...
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PostgreSQL: Is it better to use multiple databases with one schema each, or one database with multip

...chema, $customer3_documents_schema? Mh... dont seem a reliable way... and what about performance? And what about the code of my application (will be php and python)? so many schemas.. – Strae Jul 20 '09 at 15:22 ...
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design a stack such that getMinimum( ) should be O(1)

... If you have a single variable, what happens when you pop the "1" in your example? It's got to work out that the previous minimum was "2" - which it can't without scanning through everything. – Jon Skeet Mar 26 '09 at ...
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MySQL ON vs USING?

In a MySQL JOIN , what is the difference between ON and USING() ? As far as I can tell, USING() is just more convenient syntax, whereas ON allows a little more flexibility when the column names are not identical. However, that difference is so minor, you'd think they'd just do away with USI...
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Is GridFS fast and reliable enough for production?

... I don't recommend using gridfs unless you know what you are doing. GridFS is just abstraction layer which splits files for chunks and stores the files in two collections. More files - more overhead. If you expect files be pretty the same size, not exceeding 32M or so - yo...
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Is a Python list guaranteed to have its elements stay in the order they are inserted in?

... what if I return a local list from a function and use that in the calling function. That is def fn_1(): lst = [] lst.append(1) lst.append(2) return lst and def fn_2(): print(fn_1()) Will the order be same ALWAYS irrespective ...
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App.Config Transformation for projects which are not Web Projects in Visual Studio?

...u'll get a web.debug.config and a web.release.config. You can make a web.whatever.config if you like, as long as the name lines up with a configuration profile. These files are just the changes you want made, not a complete copy of your web.config. You might think you'd want to use XSLT...
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When should I use a table variable vs temporary table in sql server?

...t of Ids values to use them in others query inside the Store procedure. So what do you recommend me? – Jeancarlo Fontalvo Nov 9 '16 at 22:53 ...