defstruct

[Dave Thomas]

Would there be any support for extending defstruct so that

defstruct Person, name: "", age: 21

was a shortcut for

defmodule Person
  defstruct name: "", age: 21
end

[Josh Adams]

I like it.  I do this quite often, as you might guess.  If it's not in the language, there will be a commonly used library of some sort whose sole purpose is to provide a similar macro, I'd bet my arms on it.

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Josh Adams

[meh.]

Totally agree on this, I thought it was already the case.

[José Valim]

That won't be the case for now. Structs are different than records. Cases where you define a module simply to define a struct should be more uncommon, I expect it to rather have struct-related functions the majority of the time.

So having only defstruct/1 will help send this message across. After v0.13 is out and we are more familiar with structs, we can re-evaluate the shortcut syntax again.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Lead Developer

[Juan Uys]

Conversely, I'd like to see 

defmodule Person defstruct do

name: ""

age: 21

end end

[Akio Burns]

Has there been any further consideration on this topic? Structs are great, but they feel severely limited without the ability to easily and cleanly define arbitrarily named structs.

[Paul Schoenfelder]

I definitely wouldn't call this a severe limitation, but it would be a nice-to-have for readability. That said, I haven't actually run into any cases where I would've used the shorthand syntax - as José mentioned in his original reply, the vast majority of the time, structs have functions that go with them, or at the very least, typespecs. 

I do think it's possible for there to be cases where the shorthand syntax would be used, but I have to say that I haven't seen that in the wild, or in my own projects yet, so I can't say the need is particularly dire to have this in the standard library. It's easy to implement this as a macro in your own projects if it's a common need though. I think a real-world use case which demonstrates the value would go a long way towards making your case.

Paul

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[Louis Pop]

I use a lot of structs, so I'd like this shorthand. I don't think wrapping the current syntax in a module is a problem though.

You couldn't really implement this as a macro and save any typing as you'd need to require the macro before using it, which would probably be about the same amount of characters.

Cheers,

Louis 

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[Akio Burns]

I think the nature of structs in their present state—being visually tied to a `defmodule`—limits the thinking around them. I think that given the ability to create structs "at-will", opportunities will present themselves where one would've previously used a tuple or a plain map.

Some contrived examples:

defmodule Rectangle do
  defstruct Point, x: 0, y: 0

  ...
end

defmodule User do
  defstruct Name, first: "", middle: "", last: ""

  ...
end

I will admit that I have no direct experience to back up these claims though. I'll implement the macro in some of my own projects and try it out.

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