How Can Constructors Solve Nil Pointer Panics When Initializing Go Structs?

Using Constructors to Initialize Struct Members in Go

Initializing struct members can be challenging, especially for beginners. Let's delve into an issue where creating a new struct instance ("sm") and calling a function on it ("sm.Put") resulted in a panic due to a nil pointer.

Problem:

<br>import "sync"</p>
<p>type SyncMap struct {</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">    lock *sync.RWMutex
    hm map[string]string

Copy after login

}
func (m *SyncMap) Put (k, v string) {

    m.lock.Lock()
    defer m.lock.Unlock()

    m.hm[k] = v, true

}

func main() {

    sm := new(SyncMap)
    sm.Put("Test, "Test") // Panic

}

This code fails because both the lock and hm fields are uninitialized.

Workaround (Not Ideal):

One workaround was to add an Init function and manually initialize the fields after creating the instance:

<br>func (m *SyncMap) Init() {</p>
<div class="code" style="position:relative; padding:0px; margin:0px;"><pre class="brush:php;toolbar:false">    m.hm = make(map[string]string)
    m.lock = new(sync.RWMutex)

Copy after login