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What __init__ and self do on Python?
...to declare it explicitly. When you create an instance of the A class and call its methods, it will be passed automatically, as in ...
a = A() # We do not pass any argument to the __init__ method
a.method_a('Sailor!') # We only pass a single argument
The __init__ method is roughly w...
What does the restrict keyword mean in C++?
...
A restrict-qualified pointer (or reference)...
! ...is basically a
promise to the compiler that for the
scope of the pointer, the target of the pointer will only
be accessed through that pointer (and pointers copied
from it).
In C++ compilers that support it i...
Multiple Models in a single django ModelForm?
...
But how? Usually a FormView only has a single form_class assigned to it.
– erikbwork
Oct 7 '16 at 17:42
...
C++ Redefinition Header Files (winsock2.h)
...
I'm not including <windows.h> at all, I know <winsock2.h> does its for me.
– akif
Sep 3 '09 at 11:26
2
...
Append an object to a list in R in amortized constant time, O(1)?
...irthday. Some kind readers keep repeating any shortcomings with it, so by all means also see some of the comments below. One suggestion for list types:
newlist <- list(oldlist, list(someobj))
In general, R types can make it hard to have one and just one idiom for all types and uses.
...
Count number of records returned by group by
...his to DISTINCT COUNT() OVER(), and the query performance improved dramatically.
– Joe Aldrich
Sep 20 '17 at 13:33
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show 3 more comments
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What's the bad magic number error?
...the pyc file or trying to run a pyc from a different version of python (usually later) than your interpreter.
If they are your pyc files, just delete them and let the interpreter re-compile the py files. On UNIX type systems, that could be something as simple as:
rm *.pyc
or:
find . -name '*.py...
How to check a string for specific characters?
...r other characters.
... or
pattern = re.compile(r'\d\$,')
if pattern.findall(s):
print('Found')
else
print('Not found')
... or
chars = set('0123456789$,')
if any((c in chars) for c in s):
print('Found')
else:
print('Not Found')
[Edit: added the '$' in s answers]
...
What is a “callable”?
...t's clear what a metaclass is , there is an associated concept that I use all the time without knowing what it really means.
...
How to print a query string with parameter values when using Hibernate
...he the following categories:
org.hibernate.SQL - set to debug to log all SQL DML statements as they are executed
org.hibernate.type - set to trace to log all JDBC parameters
So a log4j configuration could look like:
# logs the SQL statements
log4j.logger.org.hibernate.SQL=debug
# Logs the...