TsAccess - Getters/Setters generator for TypedStruct

tino415

Hello,

recently I started using TypedStruct and also for quite some time I have problem with typos when using structs in elixir, mainly that struct.fiewld_name is not reported during compile time. So I was playing with idea to create plugin for TypedStruct that would generate getter and setter functions for struct. Good thing is, that when I do typo in function name, code don’t compile, another good thing is that it also generate typespecs, so I assume that dialyzer should report when I try to pass wrong type to setter (untested). I used @before_compile and module attributes that TypedStruct is adding to module:

Example:

defmodule Example do
  @before_compile TsAccess
  use TypedStruct

  typedstruct do
    field(:name, :string)
  end
end

iex> Example.name(%Example{}, "John Doe")
%Example{name: "John Doe"}

iex> Example.name(%Example{name: "John Doe"})
"John Doe"

I’m also thinking to do another library (or as another feature to this one) that would generate lenses

What do you think?

9 comments

#library #typedstruct #tsaccess

3 1972 9

2020-06-08 23:44:56 UTC

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LukeWood

Will these throw an error if given a map?

Will these preserve the struct type when setting a value?

If so seems great!

Post #1

tino415

Yes (it did not, but great idea so I added it :D)
Yes

Thank you for feedback

Post #2

tino415

Since it is mi first try at doing library for elixir, CR and API critique is welcomed

Post #3

LukeWood

Exceptional! Thanks, this is awesome!

Post #4

tino415

Hello again, I just published version 0.5.0 in which typedstruct is not neceseary anymore and also explicit mode was added where you can define getters explicitly:

defmodule Example do
  use TsAccess, explicit: true
  defstruct [
    :accesible,
    :gettable,
    :settable
  ]

  defaccessor :accessible
 
  defgetter :gettable

  defsetter :settable
end

All macros support also setting of attribute type:

defsetter :name, String.t()

In case of nonexplicit mode without typed struct, types for specs can by set using @types module attribute:

defmodule Example do
  use TsAccess

  @types [
    name: String.t()
  ]
  defstruct [
    :name
  ]
end

Hope someone find this usable :slight_smile:

Post #5

tino415

0.6.0 I also added lenses generator (base on elixir Access module) generated functions looks like:

get_in(example, [Example.name_lens()])

Post #6

tino415

After some sleep I realized that I don’t need postfix _lens, so now lenses are just field functions without arguments a.k.a get_in(example, [Example.name]) function with postfix _lens are generated with deprecation warning. Also any other ideas how further improve it? I have several:

in implicit mode add exclude, only to using
add prefix, postfix or callback to generate function names
explicit deflens, but this is little bit complicated since I don’t know how to check if field exists
add alias option to defsetter, defgetter and defaccesor
add onli, exclud, onli to defaccessor (in case of explicit lens, to choose what should by generated)

Feedback is welcomed

Post #7