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Rails: How does the respond_to block work?
... a bit. The entire class (responder) becomes the method implementation. In order to leverage method_missing, we need an instance of the class, so we're obliged to pass a callback into which they pass the method-like object. For someone who has coded in C-like languages for 20 some years, this is ver...
What is the performance cost of having a virtual method in a C++ class?
...
I ran some timings on a 3ghz in-order PowerPC processor. On that architecture, a virtual function call costs 7 nanoseconds longer than a direct (non-virtual) function call.
So, not really worth worrying about the cost unless the function is something lik...
How do synchronized static methods work in Java and can I use it for loading Hibernate entities?
... Any fast food restaurant uses multithread. One thread takes you order and use another thread to prepare it, and continues with the next customer. The synchronization point works only when they interchange information to know what to prepare. Following a model like that really simplifies ...
Getting the max value of an enum
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Enum.GetValues() seems to return the values in order, so you can do something like this:
// given this enum:
public enum Foo
{
Fizz = 3,
Bar = 1,
Bang = 2
}
// this gets Fizz
var lastFoo = Enum.GetValues(typeof(Foo)).Cast<Foo>().Last();
Edit
For th...
What does the slash mean in help() output?
...and there are only a few arguments which will always be passed in the same order.
Use keyword-only when names have meaning and the function definition is more understandable by being explicit with names.
If the function ends with /
def foo(p1, p2, /)
This means all functional arguments a...
How exactly does the callstack work?
...called function prologue and epilogue, respectively.
Inside the frame the order of the variables is completely unspecified; Compilers "reorder" the positions of local variables inside a frame appropriately to optimize their alignment so the processor can fetch them as quickly as possible. The cruci...
How do I sort unicode strings alphabetically in Python?
...de string s, it uses the code:
spec_dict = {'Å':'A', 'Ä':'A'}
def spec_order(s):
return ''.join([spec_dict.get(ch, ch) for ch in s])
Python has a much better, faster and more concise way to perform this auxiliary task (on Unicode strings -- the analogous method for byte strings has a diffe...
How to change the CHARACTER SET (and COLLATION) throughout a database?
...the utf8 character set is only a subset of the real UTF8 character set. In order to save one byte of storage, the Mysql team decided to store only three bytes of a UTF8 characters instead of the full four-bytes. That means that some east asian language and emoji aren't fully supported. To make sure ...
Relative imports in Python 2.7
...ia sys.path . Additional code that manipulates sys.path would be needed in order for direct execution to work without the top level package already being importable." -- this is the most disturbing bit to me since this "additional code" is actually quite long and can't be stored elsewhere in package...
Selecting multiple columns in a pandas dataframe
...mns, like df.ix[0, 'Col1':'Col5']. That gets all columns that happen to be ordered between Col1 and Col5 in the df.columns array. It is incorrect to say that ix indexes rows. That is just its most basic use. It also supports much more indexing than that. So, ix is perfectly general for this question...