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async.series(tasks, afterTasksCallback) will execute a set of tasks. Each task are executed after another. If a task fails, async stops immediately the execution and jump into the main callback. When tasks are finished successfully, async call the "master" callback with all errors and all...

async.waterfall(tasks, afterTasksCallback) will execute a set of tasks. Each task are executed after another, and the result of a task is passed to the next task. As async.series(), if a task fails, async stop the execution and call immediately the main callback. When tasks are finished successfull...

extern int var; static int var; /* Undefined behaviour */ C11, §6.2.2, 7 says: If, within a translation unit, the same identifier appears with both internal and external linkage, the behavior is undefined. Note that if an prior declaration of an identifier is visible then it'll have the pri...

Use the yum command to manage packages in Enterprise Linux-based operating systems: yum install php This installs a minimal install of PHP including some common features. If you need additional modules, you will need to install them separately. Once again, you can use yum to search for these pac...

One of Angular's strength's is client-side form validation. Dealing with traditional form inputs and having to use interrogative jQuery-style processing can be time-consuming and finicky. Angular allows you to produce professional interactive forms relatively easily. The ng-model directive provide...

install the required Microsoft.SqlServer.Types assembly; they are not installed by default, and are available from Microsoft here as "Microsoft® System CLR Types for Microsoft® SQL Server® 2012" - note that there are separate installers for x86 and x64. install Dapper.EntityFramew...

When using Access you can retrieve data using queries. These queries are built using Structured Query Language (SQL). Understanding SQL is important because it can help build better, more useful queries. When creating queries in Access, you can switch to "SQL View". An example of a "...

When you wish to combine the results of multiple tables or queries with similar fields together into a single resulting data set without performing any relational joins (i.e. you want to list one dataset immediately after the other), you will use a UNION query. However, it is notable that these quer...

The BOM (Browser Object Model) contains objects that represent the current browser window and components; objects that model things like history, device's screen, etc The topmost object in BOM is the window object, which represents the current browser window or tab. Document: represents current...

An awk consists of patterns and actions, enclosed in curly brackets, to be taken if a pattern matches. The most basic pattern is the empty pattern, which matches any record. The most basic action is the empty action, which is equivalent to { print }, which is, in turn, equivalent to { print $0 }. If...

# example data DT = data.table(Titanic) Suppose we want to see each class only if a majority survived: DT[, if (sum(N[Survived=="Yes"]) > sum(N[Survived=="No"]) ) .SD, by=Class] # Class Sex Age Survived N # 1: 1st Male Child No 0 # 2: 1st Fema...

Delete all nodes MATCH (n) DETACH DELETE n DETACH doesn't work in older versions(less then 2.3), for previous versions use MATCH (n) OPTIONAL MATCH (n)-[r]-() DELETE n, r Delete all nodes of a specific label MATCH (n:Book) DELETE n

A quick note before actually installing RabbitMQ: Ubuntu 14.04's Erlang packages have issues if you are using SSL with RabbitMQ, so you'll need to install a newer version than what the Ubuntu package maintainers provide, so use the binaries at https://www.erlang-solutions.com/resources/download.html...

Monotonic predicates can be debugged by applying declarative reasoning. In pure Prolog, a programming mistake can lead to one or all of the following phenomena: the predicate incorrectly succeeds in a case where it should fail the predicate incorrectly fails in a case where it should succeed t...

Examples of monotonic predicates are: unification with (=)/2 or unify_with_occurs_check/2 dif/2, expressing disequality of terms CLP(FD) constraints like (#=)/2 and (#>)/2, using a monotonic execution mode. Prolog predicates that only use monotonic goals are themselves monotonic. Monoton...

Here are examples of predicates that are not monotonic: meta-logical predicates like var/1, integer/1 etc. term comparison predicates like (@<)/2 and (@>=)/2 predicates that use !/0, (\+)/1 and other constructs that break monotonicity all-solutions predicates like findall/3 and setof/3. ...

Here are examples of how to use monotonic predicates instead of impure, non-monotonic constructs in your programs: dif/2 is meant to be used instead of non-monotonic constructs like (\=)/2 arithmetic constraints (CLP(FD), CLP(Q) and others) are meant to be used instead of moded arithmetic predi...

It is sometimes argued that, for the sake of efficiency, we must accept the use of non-monotonic constructs in real-world Prolog programs. There is no evidence for this. Recent research indicates that the pure monotonic subset of Prolog may not only be sufficient to express most real-world programs...

It is deemed best practice to always use Option Explicit in VBA as it forces the developer to declare all their variables before use. This has other benefits too, such as auto-capitalization for declared variable names and IntelliSense. Option Explicit Sub OptionExplicit() Dim a As Integer ...

Option Compare Binary Binary comparison makes all checks for string equality within a module/class case sensitive. Technically, with this option, string comparisons are performed using sort order of the binary representations of each character. A < B < E < Z < a < b < e < z ...