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What characters are allowed in an email address?

... See RFC 5322: Internet Message Format and, to a lesser extent, RFC 5321: Simple Mail Transfer Protocol. RFC 822 also covers email addresses, but it deals mostly with its structure: addr-spec = local-part "@" domain ; global address local-part ...
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What is the best way to implement nested dictionaries?

...ython? This is a bad idea, don't do it. Instead, use a regular dictionary and use dict.setdefault where apropos, so when keys are missing under normal usage you get the expected KeyError. If you insist on getting this behavior, here's how to shoot yourself in the foot: Implement __missing__ on a di...
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Java Delegates?

...same effect by using reflection to get Method objects you can then invoke, and the other way is to create an interface with a single 'invoke' or 'execute' method, and then instantiate them to call the method your interested in (i.e. using an anonymous inner class). You might also find this article ...
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What is the difference between float and double?

I've read about the difference between double precision and single precision. However, in most cases, float and double seem to be interchangeable, i.e. using one or the other does not seem to affect the results. Is this really the case? When are floats and doubles interchangeable? What are the d...
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Can't start site in IIS (use by another process)

... Check using netstat -aon or netstat -aon | findstr 0.0:80 in a command prompt to see which Process Id is LISTENING to port :80 and then watch for that Process Id (PID) in Task Manager with view->select columns-> process id checked. End that process, restart IIS and you are done. (Note:...
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How can I profile C++ code running on Linux?

... a profiler, use one of the suggested ones. However, if you're in a hurry and you can manually interrupt your program under the debugger while it's being subjectively slow, there's a simple way to find performance problems. Just halt it several times, and each time look at the call stack. If there...
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What to put in a python module docstring? [closed]

Ok, so I've read both PEP 8 and PEP 257 , and I've written lots of docstrings for functions and classes, but I'm a little unsure about what should go in a module docstring. I figured, at a minimum, it should document the functions and classes that the module exports, but I've also seen a few mod...
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What is the most effective way for float and double comparison?

...ing problems were: The implicit presumption in an algorithm that if a==b and b==c then a==c. Using the same epsilon for lines measured in inches and lines measured in mils (.001 inch). That is a==b but 1000a!=1000b. (This is why AlmostEqual2sComplement asks for the epsilon or max ULPS). The use o...
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Is floating point math broken?

...is like this. In most programming languages, it is based on the IEEE 754 standard. The crux of the problem is that numbers are represented in this format as a whole number times a power of two; rational numbers (such as 0.1, which is 1/10) whose denominator is not a power of two cannot be exactly re...
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What is a software framework? [closed]

...o the measuring 1000 times; obviously, you would make a frame of 5m by 5m, and then with the help of it you would be able to cut 1000 pieces of paper in less time. So, what you did was make a framework which would do a specific type of task. Instead of performing the same type of task again and agai...