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os.access is much better solution to check whether directory exists and it's accesable for reading and writing. import os path = "/home/myFiles/directory1" ## Check if path exists os.access(path, os.F_OK) ## Check if path is Readable os.access(path, os.R_OK) ## Check if path i...

Multiple transforms can be applied to an element in one property like this: transform: rotate(15deg) translateX(200px); This will rotate the element 15 degrees clockwise and then translate it 200px to the right. In chained transforms, the coordinate system moves with the element. This means tha...

When reading multiple values from a channel, using range is a common pattern: func foo() chan int { ch := make(chan int) go func() { ch <- 1 ch <- 2 ch <- 3 close(ch) }() return ch } func main() { for n := r...

To refresh the page every five seconds, add this meta element in the head element: <meta http-equiv="refresh" content="5"> CAUTION! While this is a valid command, it is recommended that you do not use it because of its negative effects on user experience. Refreshing the...

This error appears while trying to update or delete records without including the WHERE clause that uses the KEY column. To execute the delete or update anyway - type: SET SQL_SAFE_UPDATES = 0; To enable the safe mode again - type: SET SQL_SAFE_UPDATES = 1;

Agents can be added to a JVM at runtime. To load an agent you will need to use the Attach API's VirtualMachine.attatch(String id). You can then load a compiled agent jar with the following method: public static void loadAgent(String agentPath) { String vmName = ManagementFactory.getRuntimeMXBe...

The Premain class will contain the method "premain(String agentArgs Instrumentation inst)" Here is an example: import java.lang.instrument.Instrumentation; public class PremainExample { public static void premain(String agentArgs, Instrumentation inst) { System.out.print...

let list1 = [ 1; 2 ] let list2 = [ 1 .. 100 ] // Accessing an element printfn "%A" list1.[0] // Pattern matching let rec patternMatch aList = match aList with | [] -> printfn "This is an empty list" | head::tail -> printfn "This list consists o...

Create a .gitattributes file in the project root containing: * text=auto This will result in all text files (as identified by Git) being committed with LF, but checked out according to the host operating system default. This is equivalent to the recommended core.autocrlf defaults of: input o...

__construct() is the most common magic method in PHP, because it is used to set up a class when it is initialized. The opposite of the __construct() method is the __destruct() method. This method is called when there are no more references to an object that you created or when you force its deletion...

When contributors add to a project from different machines or operating systems, it may happen that they use different email addresses or names for this, which will fragment contributor lists and statistics. Running git shortlog -sn to get a list of contributors and the number of commits by them co...

Once setup is completed. Copy the code below to index.android.js or to index.ios.js file to use the props. import React, { Component } from 'react'; import { AppRegistry, Text, View } from 'react-native'; class Greeting extends Component { render() { return ( <Text>Hello {t...

This example is showing how to query a database with database/sql, taking as example a MySql database. package main import ( "log" "fmt" "database/sql" _ "github.com/go-sql-driver/mysql" ) func main() { dsn := "mysql_usern...

It's a very common extension that allows type classes with multiple type parameters. You can think of MPTC as a relation between types. {-# LANGUAGE MultiParamTypeClasses #-} class Convertable a b where convert :: a -> b instance Convertable Int Float where convert i = fromIntegr...

A syntactic extension that allows applying the tuple constructor (which is an operator) in a section way: (a,b) == (,) a b -- With TupleSections (a,b) == (,) a b == (a,) b == (,b) a N-tuples It also works for tuples with arity greater than two (,2,) 1 3 == (1,2,3) Mapping This can be u...

An extension that allows you to use Unicode characters in lieu of certain built-in operators and names. ASCIIUnicodeUse(s)::∷has type->→function types, lambdas, case branches, etc.=>⇒class constraintsforall∀explicit polymorphism<-←do notation*★the type (or kind) of types (e.g., Int :: ★)&g...

This is a type system extension that allows types that are existentially quantified, or, in other words, have type variables that only get instantiated at runtime†. A value of existential type is similar to an abstract-base-class reference in OO languages: you don't know the exact type in contains,...

The following expressions are sequenced: a && b a || b a , b a ? b : c for ( a ; b ; c ) { ... } In all cases, the expression a is fully evaluated and all side effects are applied before either b or c are evaluated. In the fourth case, only one of b or c will be evaluated. In the l...

C11 The following expressions are unsequenced: a + b; a - b; a * b; a / b; a % b; a & b; a | b; In the above examples, the expression a may be evaluated before or after the expression b, b may be evaluated before a, or they may even be intermixed if they correspond to several instruct...

In this example, documentation for the local function baz (defined in foo.m) can be accessed either by the resulting link in help foo, or directly through help foo>baz. function bar = foo %This is documentation for FOO. % See also foo>baz % This wont be printed, because there is a line w...