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ImportError: Cannot import name X
...r different files named: main, vector, entity and physics. I will not post all the code, just the imports, because I think that's where the error is. (If you want, I can post more)
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Why switch is faster than if
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Because there are special bytecodes that allow efficient switch statement evaluation when there are a lot of cases.
If implemented with IF-statements you would have a check, a jump to the next clause, a check, a jump to the next clause and so on. With switch the JV...
Short description of the scoping rules?
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Actually, a concise rule for Python Scope resolution, from Learning Python, 3rd. Ed.. (These rules are specific to variable names, not attributes. If you reference it without a period, these rules apply.)
LEGB Rule
Local — N...
What is the copy-and-swap idiom?
...s arguably the most nuanced and difficult. How should it be done? What pitfalls need to be avoided?
The copy-and-swap idiom is the solution, and elegantly assists the assignment operator in achieving two things: avoiding code duplication, and providing a strong exception guarantee.
How does it wor...
Does Java casting introduce overhead? Why?
...casting, when you cast from a type to a wider type, which is done automatically and there is no overhead:
String s = "Cast";
Object o = s; // implicit casting
Explicit casting, when you go from a wider type to a more narrow one. For this case, you must explicitly use casting like that:
Object o ...
UIPanGestureRecognizer - Only vertical or horizontal
I have a view that has a UIPanGestureRecognizer to drag the view vertically. So in the recognizer callback, I only update the y-coordinate to move it. The superview of this view, has a UIPanGestureRecognizer that will drag the view horizontally, just updating the x-coordinate.
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Why use prefixes on member variables in C++ classes
...before a capital letter in a word is reserved.
For example:
_Foo
_L
are all reserved words while
_foo
_l
are not. There are other situations where leading underscores before lowercase letters are not allowed. In my specific case, I found the _L happened to be reserved by Visual C++ 2005 and ...
What is the difference between LL and LR parsing?
...te by hand, but they are less powerful than LR parsers and accept a much smaller set of grammars than LR parsers do. LR parsers come in many flavors (LR(0), SLR(1), LALR(1), LR(1), IELR(1), GLR(0), etc.) and are far more powerful. They also tend to have much more complex and are almost always gene...
Why use def main()? [duplicate]
...ink I still have something else to add.
Reasons to have that if statement calling main() (in no particular order):
Other languages (like C and Java) have a main() function that is called when the program is executed. Using this if, we can make Python behave like them, which feels more familiar for ...
How to convert std::string to NSString?
...dent encoding who value is derived from user's default language and potentially other factors. The use of this encoding might sometimes be needed when interpreting user documents with unknown encodings, in the absence of other hints. This encoding should be used rarely, if at all. Note that some po...