How to constant ?!

[Ashutosh Baghel]

Hello folks,

I want to declare a few variables constant. But I guess there is nothing as "Constant" type in GoLang. How do I achieve this in GoLang?

[David Riley]

On May 28, 2019, at 8:12 AM, Ashutosh Baghel <baghel....@gmail.com> wrote:
>
> Hello folks,
>
> I want to declare a few variables constant. But I guess there is nothing as "Constant" type in GoLang. How do I achieve this in GoLang?

https://tour.golang.org/basics/15

[Trig]

package main

import "fmt"

const (
     ExposedConstant  = "1"  // exposed outside of package
     internalConstant = "2"  // for use anywhere in package only
)

func main() {
     const functionConstant = "3"  // usable anywhere in main func

     fmt.Println(ExposedConstant, internalConstant, functionConstant)
}

[Trig]

Whoops... forgot to add the top line to the code syntax.  I really wish you could edit existing posts in this group.

[David Finkel]

On Tue, May 28, 2019 at 11:04 AM Trig <edb...@gmail.com> wrote:

Whoops... forgot to add the top line to the code syntax.  I really wish you could edit existing posts in this group.

On Tuesday, May 28, 2019 at 10:03:05 AM UTC-5, Trig wrote:

package main

import "fmt"

const (
     ExposedConstant  = "1"  // exposed outside of package
     internalConstant = "2"  // for use anywhere in package only
)

func main() {
     const functionConstant = "3"  // usable anywhere in main func

     fmt.Println(ExposedConstant, internalConstant, functionConstant)
}

https://golang.org/ref/spec#Constants

Note that the const keyword can only be used with primitive types.

For more complicated values, I tend to use functions/methods. (the GC compiler's inliner is smart enough to inline a function call to a function with exactly one return statement containing a small struct literal)

e.g. https://play.golang.org/p/AaLXcZ-CYEY

package main

import "fmt"

// Foo is a struct
type Foo struct {
	A int
	B string
}

// DefaultFoo returns a useful default struct
func DefaultFoo() Foo {
	return Foo{
		A: 1,
		B: "abcd",
	}
}

// Bim does something
func Bim() {
	fmt.Printf("%+v\n", DefaultFoo())
}

On Tuesday, May 28, 2019 at 7:12:06 AM UTC-5, Ashutosh Baghel wrote:

Hello folks,

I want to declare a few variables constant. But I guess there is nothing as "Constant" type in GoLang. How do I achieve this in GoLang?

For those with an interest in the inlining behavior, Matt Godbolt's Compiler Explorer supports Go. Here's a small modification of the example above (mostly just moved it out of the main package and removed the imports to reduce the amount of code generated): https://go.godbolt.org/z/izOJVU

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