Go common mistakes - Part 1

Go common mistakes - Part 1

ยท

2 min read

Albert Einstein had a quote

Anyone who has never made a mistake has never tried anything new.

But one shouldn't repeat his mistakes. It is best to learn from them and capture them forever.

Here are the mistakes I have made when I started to learn Go.

1. Import for side effect

Issue

package main

import (
    "encoding/base64"
    "fmt"
    "image" // missing import for package image/jpeg
    "log"
    "strings"
)

func main() {
    reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
    m, _, err := image.Decode(reader)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(m)
}

const data = `
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UVtgtmY4nZEa8Ak9aqFv3rfSiiu1nMeifDv/AJF+T/r4f+QrqqKKQwzQenNFFMCOKFIgNuThdoJ5OPSk
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0HwyBXGeRjmrcUhMg2ghezd//rUUVcTKW5s2jZtY/QDaOKKKK8ip8bPRj8KP/9k=
`
image: unknown format

Solution

package main

import (
    "encoding/base64"
    "fmt"
    "image"
    "log"
    "strings"
    // Package image/jpeg is not used explicitly in the code below,
    // but is imported for its initialization side-effect, which allows
    // image.Decode to understand JPEG formatted images.
    _ "image/jpeg"
)

func main() {
    reader := base64.NewDecoder(base64.StdEncoding, strings.NewReader(data))
    m, _, err := image.Decode(reader)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(m)
}

const data = `
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`
&{[44 44 45 46 46 47 48 48 42 42 42 42 42 42 42 42 42 42 42 43 45 49 52 53 46 46 46 4 ... 165 169] 160 80 YCbCrSubsampleRatio420 (0,0)-(150,103)}

2. Unexpected new-line

Issue

func main() {
    const fruits = []string{
        "cherry",
        "banana" // Missing a comma here `,`
    }

    fmt.Println(fruits)
}
./model.go:6:17: syntax error: unexpected newline, expecting comma or }

Solution

func main() {
    const fruits = []string{
        "cherry",
        "banana",
    }

    fmt.Println(fruits) // ["cherry", "banana"]
}

3. Unaltered strings

Issue: Strings are immutable in Go

func main() {
    fruit := "cherry"
    fruit[0] = "C"

    fmt.Println(fruit) // error here
}
./model.go:7:14: cannot assign to fruit[0] (strings are immutable)

Solution

func main() {
    fruit := []rune("cherry")
    fruit[0] = 'C'
    s := string(fruit)
    fmt.Println(s) // Cherry
}

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