One of the best loggers in Golang:

- https://github.com/sirupsen/logrus

#golang #go #logrus

environments in Golang:

To set a key/value pair, use os.Setenv. To get a value for a key, use os.Getenv. This will return an empty string if the key isn’t present in the environment.

Use os.Environ to list all key/value pairs in the environment. This returns a slice of strings in the form KEY=value. You can strings.Split them to get the key and value. Here we print all the keys:

package main

import (
        "os"
        "strings"
        "fmt"
)

func main() {
    os.Setenv("FOO", "1")
    fmt.Println("FOO:", os.Getenv("FOO"))
    fmt.Println("BAR:", os.Getenv("BAR"))

    fmt.Println()
    for _, e := range os.Environ() {
        pair := strings.Split(e, "=")
        fmt.Println(pair[0])
    }
}

#golang #go #env #environment #environment_variables #range #setenv #getenv #environ

If you want to implement "Python Capitalize" method in Go:

strings.Title(strings.ToLower("MYNAME")) // output: Myname

There is another method called ToTitle which is used for one character long (but to letters):

str := "dz"
fmt.Println(strings.ToTitle(str)) // output: Dz

#python #golang #go #ToLower #Title #strings #capitalize #ToTitle

How to block forever in Go?

- https://blog.sgmansfield.com/2016/06/how-to-block-forever-in-go/

#golang #go #sync #block

A very great talk by Brian Ketelsen about microservices using go-micro:

- https://www.youtube.com/watch?v=OcjMi9cXItY

#youtube #golang #go #microservice #gomicro #micro

Slices are far more efficient than Arrays in Go. Assigning one array to another copies all the elements while in Slice it refers to the underlying Array.

There are major differences between the ways arrays work in Go and C. In Go,

- Arrays are values. Assigning one array to another copies all the elements.
- In particular, if you pass an array to a function, it will receive a copy of the array, not a pointer to it.
- The size of an array is part of its type. The types [10]int and [20]int are distinct.

*NOTE:* The value property can be useful but also expensive; if you want C-like behavior and efficiency, you can pass a pointer to the array.

Read more about arrays and slices here:

- https://golang.org/doc/effective_go.html#arrays

#go #arrays #slices

A very great article about Go styling and how to code readble, maintainable code in Go (it can be used in other languages too):

- https://dave.cheney.net/practical-go/presentations/qcon-china.html#_always_document_public_symbols

#golang #go #maintainable #readble_code

Let's talk a little bit about WaitGroup in sync library. First things first, the documentation is here:
- https://golang.org/pkg/sync/#WaitGroup

A WaitGroup waits for a collection of goroutines to finish. The main goroutine calls Add to set the number of goroutines to wait for. Then each of the goroutines runs and calls Done when finished. At the same time, Wait can be used to block until all goroutines have finished.

With an example it will be crystal clear. Let's say we have a script that fetches URLs concurrently and we want to wait using WaitGroup until all the fetches are complete:

package main

import (
        "sync"
)

type httpPkg struct{}

func (httpPkg) Get(url string) {}

var http httpPkg

func main() {
        var wg sync.WaitGroup
        var urls = []string{
                "http://www.golang.org/",
                "http://www.google.com/",
                "http://www.somestupidname.com/",
        }
        for _, url := range urls {
                // Increment the WaitGroup counter.
                wg.Add(1) 
                // Launch a goroutine to fetch the URL.
                go func(url string) {
                        // Decrement the counter when the goroutine completes.
                        defer wg.Done()
                        // Fetch the URL.
                        http.Get(url)
                }(url)
        }
        // Wait for all HTTP fetches to complete.
        wg.Wait()
}

First we create a WaitGroup called wg and using range loop through the URLs on each iterration we use Add to increment WaitGroup counter/queue and run an anonymous function that gets a URL. When func i
s done getting the URL, defer will be run and Done decrement the counter in WaitGroup. Finally we use Wait to actually wait for all http calls to get completed.

NOTE: anonymous function is preceded with go keyword that runs the function concurrently.

#golang #go #sync #WaitGroup #Done #Add #Wait

GJSON is a Go package that provides a fast and simple way to get values from a json document. It has features such as one line retrieval, dot notation paths, iteration, and parsing json lines.

Las mere:
https://github.com/tidwall/gjson

#golang #go #gjson

https://go-proverbs.github.io/

#go #golang #proverbs