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How to decorate a class?
...
Example:
def substitute_init(self, id, *args, **kwargs):
pass
class FooMeta(type):
def __new__(cls, name, bases, attrs):
attrs['__init__'] = substitute_init
return super(FooMeta, cls).__new__(cls, name, bases, attrs)
class Foo(object):
__metaclass__ = FooMeta
d...
How to select rows from a DataFrame based on column values?
... example,
import pandas as pd
import numpy as np
df = pd.DataFrame({'A': 'foo bar foo bar foo bar foo foo'.split(),
'B': 'one one two three two two one three'.split(),
'C': np.arange(8), 'D': np.arange(8) * 2})
print(df)
# A B C D
# 0 foo one ...
Overloading Macro on Number of Arguments
I have two macros FOO2 and FOO3 :
8 Answers
8
...
Using property() on classmethods
...method property, create the property on the metaclass.
>>> class foo(object):
... _var = 5
... class __metaclass__(type): # Python 2 syntax for metaclasses
... pass
... @classmethod
... def getvar(cls):
... return cls._var
... @classmethod
... def s...
Creating an instance of class
...
/* 1 */ Foo* foo1 = new Foo ();
Creates an object of type Foo in dynamic memory. foo1 points to it. Normally, you wouldn't use raw pointers in C++, but rather a smart pointer. If Foo was a POD-type, this would perform value-initial...
Namespace and class with the same name?
...d up in this unfortunate situation: you are writing Blah.DLL and
importing Foo.DLL and Bar.DLL, which, unfortunately, both have a type
called Foo:
// Foo.DLL:
namespace Foo { public class Foo { } }
// Bar.DLL:
namespace Bar { public class Foo { } }
// Blah.DLL:
namespace Blah
{
using Foo; ...
The easiest way to transform collection to array?
Suppose we have a Collection<Foo> . What is the best (shortest in LoC in current context) way to transform it to Foo[] ? Any well-known libraries are allowed.
...
How do you perform a left outer join using linq extension methods
...
For a (left outer) join of a table Bar with a table Foo on Foo.Foo_Id = Bar.Foo_Id in lambda notation:
var qry = Foo.GroupJoin(
Bar,
foo => foo.Foo_Id,
bar => bar.Foo_Id,
(x,y) => new { Foo = x, Bars = y })
.SelectMany(...
When to use dynamic vs. static libraries
...
Creating a static library
$$:~/static [32]> cat foo.c
#include<stdio.h>
void foo()
{
printf("\nhello world\n");
}
$$:~/static [33]> cat foo.h
#ifndef _H_FOO_H
#define _H_FOO_H
void foo();
#endif
$$:~/static [34]> cat foo2.c
#include<stdio.h>
void foo2()...
How to trim whitespace from a Bash variable?
...ine a variable containing leading, trailing, and intermediate whitespace:
FOO=' test test test '
echo -e "FOO='${FOO}'"
# > FOO=' test test test '
echo -e "length(FOO)==${#FOO}"
# > length(FOO)==16
How to remove all whitespace (denoted by [:space:] in tr):
FOO=' test test test '
FOO_NO_W...