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Which is better, return value or out parameter?
...ery rare exception to this rule.)
Aside from anything else, it stops the caller from having to declare the variable separately:
int foo;
GetValue(out foo);
vs
int foo = GetValue();
Out values also prevent method chaining like this:
Console.WriteLine(GetValue().ToString("g"));
(Indeed, that...
How do I run two commands in one line in Windows CMD?
...
Like this on all Microsoft OSes since 2000, and still good today:
dir & echo foo
If you want the second command to execute only if the first exited successfully:
dir && echo foo
The single ampersand (&) syntax to exe...
e.printStackTrace equivalent in python
... = logging.getLogger()
logger.setLevel(logging.DEBUG)
def f():
a = { 'foo': None }
# the following line will raise KeyError
b = a['bar']
def g():
f()
try:
g()
except Exception as e:
logger.error(str(e), exc_info=True)
And it will output:
'bar'
Traceback (most recent cal...
Does JavaScript have “Short-circuit” evaluation?
... in times of JIT-compiling-magic in javascript implementations, one does really want to know if something is "the standard" , or potentially subject to the implementation. The way a condition statement with Binary Logical Operators is evaluated and (short-curcuit) is a standard behavior ecma-interna...
Rails - link_to helper with data-* attribute [duplicate]
... in... Rails has a default :data hash
= link_to body, url, :data => { :foo => 'bar', :this => 'that' }
One gotcha - you must surround symbols with quotes if they include a dash:
:data => { :'foo-bar' => 'that' }
Update: In Rails 4, underscores are automatically converted to dash...
How do I forward declare an inner class? [duplicate]
...want, but here is a workaround, if you are willing to use templates:
// Foo.h
struct Foo
{
export template<class T> void Read(T it);
};
// Foo.cpp
#include "Foo.h"
#include "Container.h"
/*
struct Container
{
struct Inner { };
};
*/
export template<>
void Foo::Read<...
What is the difference between instanceof and Class.isAssignableFrom(…)?
...s Y which extends Z which extends A), results might be different.
it is usually advised to write the code first picking one of the operators (the most convenient) and then profile your code to check if there are a performance bottleneck. Maybe this operator is negligible in the context of your code,...
Automapper - how to map to constructor parameters instead of property setters
...
Use ConstructUsing
this will allow you to specify which constructor to use during the mapping. but then all of the other properties will be automatically mapped according to the conventions.
Also note that this is different from ConvertUsing in that con...
What does it mean in shell when we put a command inside dollar sign and parentheses: $(command)
... of the $ like ${HOME} gives the value of HOME. Usage of the $ like $(echo foo) means run whatever is inside the parentheses in a subshell and return that as the value. In my example, you would get foo since echo will write foo to standard out
...
How to use php serialize() and unserialize()
... and Javascript can only communicate via strings. You can pass the string "foo" very easily to Javascript. You can pass the number 1 very easily to Javascript. You can pass the boolean values true and false easily to Javascript. But how do you pass this array to Javascript?
Array ( [1] => elem 1...