Tutorial by Examples: u

std::function type erases down to a few operations. One of the things it requires is that the stored value be copyable. This causes problems in a few contexts, like lambdas storing unique ptrs. If you are using the std::function in a context where copying doesn't matter, like a thread pool where ...

/** * Created by Nick Cardoso on 03/08/16. * This is not a complete parcelable implementation, it only highlights the easiest * way to read and write your Enum values to your parcel */ public class Foo implements Parcelable { private final MyEnum myEnumVariable; private final M...

The General Query Log contains a listing of general information from client connects, disconnects, and queries. It is invaluable for debugging, yet it poses as a hindrance to performance (citation?). An example view of a General Query Log is seen below: To determine if the General Log is current...

To determine the version of Azure PowerShell that you have installed, run the following: Get-Module -ListAvailable -Name Azure -Refresh This command returns the installed version even when you haven't loaded the Azure PowerShell module in your current PowerShell session.

Azure Cmdlets let you perform some of the same actions on Azure assets through PowerShell that you would using C# code or the Azure portal. For example, these steps let you download the contents of an Azure blob into a local directory: New-Item -Path .\myblob -ItemType Directory $context = New-Az...

For more advanced regex operations it's best to use CL_ABAP_REGEX and its related classes. DATA: lv_test TYPE string, lo_regex TYPE REF TO cl_abap_regex. lv_test = 'The quick brown fox'. CREATE OBJECT lo_regex EXPORTING pattern = 'q(...)\w'. DATA(lo_matcher) = lo_regex->cr...

SQL Server 2008 R2 SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED This is the most permissive isolation level, in that it does not cause any locks at all. It specifies that statements can read all rows, including rows that have been written in transactions but not yet committed (i.e., they are...

Step 1. In your host machine (Windows/Linux/OSX), create an empty dir my_project. Step 2. Create a file named Vagrantfile with this: Vagrant.configure("2") do |config| config.vm.box = "gbarbieru/xenial" #An Ubuntu 16.04 based image config.vm.hostname = "my_project&...

The first mistake that nearly every single programmer makes is presuming that this code will work as intended: float total = 0; for(float a = 0; a != 2; a += 0.01f) { total += a; } The novice programmer assumes that this will sum up every single number in the range 0, 0.01, 0.02, 0.03, .....

Groovy's safe navigation operator allows to avoid NullPointerExceptions when accessing to methods or attributes on variables that may assume null values. It is equivalent to nullable_var == null ? null : nullable_var.myMethod() def lst = ['foo', 'bar', 'baz'] def f_value = lst.find { it.startsWi...

for numbers, a zero value evaluates to false, non zero to true int i = 0 ... if (i) print "some ${i}" else print "nothing" will print "nothing"

a string (including GStrings) evaluates to true if not null and not empty, false if null or empty def s = '' ... if (s) println 's is not empty' else println 's is empty' will print: 's is empty'

Collections and Maps evaluates to true if not null and not empty and false if null or empty /* an empty map example*/ def userInfo = [:] if (!userInfo) userInfo << ['user': 'Groot', 'species' : 'unknown' ] will add user: 'Groot' , species : 'unknown' as default userInfo since the u...

a null object reference evaluates to false, a non null reference to true, but for for strings, collections, iterators and enumerations it also takes into account the size. def m = null if (!m) println "empty" else println "${m}" will print "empty" de...

Sometimes it may be useful to have a specific asBoolean definition in your own program for some kind of objects. /** an oversimplified robot controller */ class RunController { def complexCondition int position = 0 def asBoolean() { return complexCondition(this...

Not all type erasure involves virtual inheritance, allocations, placement new, or even function pointers. What makes type erasure type erasure is that it describes a (set of) behavior(s), and takes any type that supports that behavior and wraps it up. All information that isn't in that set of beha...

The population count of a bitstring is often needed in cryptography and other applications and the problem has been widely studied. The naive way requires one iteration per bit: unsigned value = 1234; unsigned bits = 0; // accumulates the total number of bits set in `n` for (bits = 0; value; ...

my @data_array = (123, 456, 789, 'poi', 'uyt', "rew", "qas"); print Dumper @data_array; Using Data::Dumper gives an easy access to fetch list values. The Dumper returns the list values serialized in a way that looks like Perl code. Output: $VAR1 = 123; $VAR2 = 456; $VAR3 ...

Install Iron Router From the terminal: meteor add iron:router Basic configuration Router.configure({ //Any template in your routes will render to the {{> yield}} you put inside your layout template layoutTemplate: 'layout', loadingTemplate: 'loading' }); Render without d...

Many beginners to Mongo struggle with basics, such as how to insert an array, date, boolean, session variable, and so forth into a document record. This example provides some guidance on basic data inputs. Todos.insert({ text: "foo", // String listId: Session...