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What are the rules for calling the superclass constructor?
What are the C++ rules for calling the superclass constructor from a subclass one?
10 Answers
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Standard alternative to GCC's ##__VA_ARGS__ trick?
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It is possible to avoid the use of GCC's ,##__VA_ARGS__ extension if you are willing to accept some hardcoded upper limit on the number of arguments you can pass to your variadic macro, as described in Richard Hansen's answer to this question. If you do not want to hav...
How to validate an Email in PHP?
...hould be replaced by the preg family (PCRE Regex Functions). There are a small amount of differences, reading the Manual should suffice.
Update 1: As pointed out by @binaryLV:
PHP 5.3.3 and 5.2.14 had a bug related to
FILTER_VALIDATE_EMAIL, which resulted in segfault when validating
large ...
How does the @property decorator work in Python?
...is just syntactic sugar; the syntax:
@property
def foo(self): return self._foo
really means the same thing as
def foo(self): return self._foo
foo = property(foo)
so foo the function is replaced by property(foo), which we saw above is a special object. Then when you use @foo.setter(), what you ...
Python __call__ special method practical example
I know that __call__ method in a class is triggered when the instance of a class is called. However, I have no idea when I can use this special method, because one can simply create a new method and perform the same operation done in __call__ method and instead of calling the instance, you can c...
How do I initialize the base (super) class?
... and invoke their base class through super(), e.g.
class X(object):
def __init__(self, x):
pass
def doit(self, bar):
pass
class Y(X):
def __init__(self):
super(Y, self).__init__(123)
def doit(self, foo):
return super(Y, self).doit(foo)
Because python knows about old- an...
Is it possible to push a git stash to a remote repository?
...ffect either!
It would only be confusing anyway since that wouldn't fetch all stashes, only the latest one; the list of stashes is the reflog of the ref refs/stashes.
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How to change the Eclipse default workspace?
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It doesnt allow me to move this folder anywhere outside of my working folder...Is there any workarounds to move this folder into another drive?
– Laserson
Mar 17 '13 at 14:43
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Select distinct values from a table field
...ant any ordering to be applied to a query, not even the default ordering, call order_by() with no parameters.
and distinct() in the note where it discusses issues with using distinct() with ordering.
To query your DB, you just have to call:
models.Shop.objects.order_by().values('city').distinct(...
Selecting multiple columns in a pandas dataframe
...).
df1 = df[['a', 'b']]
Alternatively, if it matters to index them numerically and not by their name (say your code should automatically do this without knowing the names of the first two columns) then you can do this instead:
df1 = df.iloc[:, 0:2] # Remember that Python does not slice inclusive of...