Namespacing hack using method on empty type

[dani.m...@gmail.com]

Hi all, just saw a piece of software that make large use of methods defined on (basically) empty structs as a namespacing hack.

Example:

type Foo struct {
}

func NewFoo() Foo {
  return Foo{}
}

var (
  foo = NewFoo()
)

func (self Foo) Bar1 () {
}


func (self Foo) Bar2 () {
}

This way I can call bar1 and bar2 as if they were func exposed on the "package" foo, like this:

foo.Bar1()
foo.Bar2()

I assumed that is bad practice. What do you think?

Thanks

[atd...@gmail.com]

No it can have its uses.

It really depends on what you are doing. However, I've never done this as a way to declare some kind of namespace.

Typically, I use that in testing when I want a dummy type to implement an interface.

That's just an example.

It can be used also if you export the struct type. That allows to transfer a group of functions (closer to your idea of namespace).

Instead of exporting each function separately.

[dc0d]

Personally I do that (despite that everyone advocates against it). Just remember your struct should be just "struct{}" and nothing else. This helped me to use shorter & cleaner names for my functions - actually it converts a function pile to a batch of functions).

[Christoph Berger]

Are there any advantages over using real packages?

[Christian Joergensen]

Hi,

For starters, packages can't implement interfaces.

Cheers,

[parais...@gmail.com]

You just declared a global variable. the standard library does exactly that with http Client. I assume if it is in the std lib I don't see why you shouldn't do that yourself.

[Christoph Berger]

Hi Christian,

You’re right on this, but my question is about another aspect. The thread starter’s question was about using structs for namespaces (instead of packages). My question is, why would someone want to use empty structs for creating a name space if a package already does this. After all, packages are the natural means for creating a namespace.

Thx

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