How to Avoid Stack Overflow Errors with `fmt.Sprintf(\'% v\')` in Nested Go Structs?

Goroutine Stack Overflow Error with Nested Structs and fmt.Sprintf()

The issue arises when using fmt.Sprintf() with the "% v" format specifier in a nested struct's String() method. The "% v" format calls the String() method of each nested type recursively, leading to infinite recursion and a stack overflow error.

Consider the nested structs:

<code class="go">type ConfigOne struct {
    Daemon daemon
}

type daemon struct {
    Loglevel int
    Logfile string
}</code>

The String() method for ConfigOne is defined as:

<code class="go">func (c ConfigOne)String()  string{
    return fmt.Sprintf("%+v\n", c)
}</code>

When printing nested struct elements with fmt.Sprintf("% v", c), the "% v" format uses the value of c.String(), causing endless recursion.

To avoid this recursion, manually construct the string representing the nested struct, as shown:

<code class="go">func (c ConfigOne)String()  string{
    return fmt.Sprintf("Loglevel: %d, Logfile: %s\n", c.Daemon.Loglevel, c.Daemon.Logfile)
}</code>

This approach eliminates the recursive String() calls and allows you to control the string's contents.

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