Question

我具有以下两个功能，并且收到有关它们的透析器警告：

"Type specification 'Elixir.MyModule':calculate(arg1::'Elixir.String':t(),arg2::'Elixir.CustomType':t(),arg3::'Elixir.String':t()) -> 'ok' | 'error'; calculate(arg1::'Elixir.String':t(),arg2::'Elixir.CustomType':t(),arg3::maybe_improper_list()) -> 'ok' | 'error' is a subtype of the success typing: 'Elixir.MyModule':calculate(binary(),#{'__struct__':='Elixir.CustomType', _=>_},binary() | maybe_improper_list()) -> 'error' | 'ok'"

以下是功能：

@spec calculate(arg1 :: String.t, arg2 :: CustomType.t, arg3 :: String.t)
def calculate(arg1, %CustomType{} = arg2, arg3) when is_binary(arg1) and is_binary(arg3) do
  calculate(arg1, arg2, [arg3])
end

@spec calculate(arg1 :: String.t, arg2 :: CustomType.t, arg3 :: maybe_improper_list())
def calculate(arg1, %CustomType{prop1: val, prop2: val2}, arg3) when is_binary(arg1) and is_integer(val2) and is_binary(val) and is_list(arg3) do
...
end

我不明白为什么收到此警告。我以为这是在Elixir中编写具有不同参数类型的函数的正确方法，但是鉴于Dialyzer不断发出警告，我开始怀疑我是否在错误地编写此代码？

defmodule CustomType do
  @type t :: %CustomType{
    prop1: String.t(),
    prop2: integer(),
    prop3: String.t(),
    prop4: boolean(),
    ...
  }
end

这些是我正在运行的透析器标志：

dialyzer: [
  flags: ~w[underspecs overspecs race_conditions error_handling unmatched_returns]a
]

复制样本：

defmodule MyCustomType do
    @type t :: %MyCustomType{
        prop1: String.t(),
        prop2: integer(),
        prop3: String.t()
    }

    defstruct [:prop1, :prop2, :prop3]
end

defmodule MyModule do
    @spec calculate(String.t, 
                    MyCustomType.t, 
                    String.t) 
    :: :ok
    def calculate(arg1, %MyCustomType{} = arg2, arg3) when is_binary(arg1) and is_binary(arg3) do
        calculate(arg1, arg2, [arg3])
    end

    @spec calculate(String.t, 
                    MyCustomType.t, 
                    maybe_improper_list) 
    :: :ok
    def calculate(arg1, %MyCustomType{prop1: val, prop2: val2}, arg3) when is_binary(arg1) and is_list(arg3) and is_binary(val) and is_integer(val2) do
        :ok
    end
end

以下是我收到的警告：

      Type specification 'Elixir.MyModule':calculate
          ('Elixir.String':t(),
          'Elixir.MyCustomType':t(),
          'Elixir.String':t()) ->
             'ok';
         ('Elixir.String':t(),
          'Elixir.MyCustomType':t(),
          maybe_improper_list()) ->
             'ok' is a subtype of the success typing: 'Elixir.MyModule':calculate
          (binary(),
          #{'__struct__' := 'Elixir.MyCustomType',
            'prop1' := binary(),
            'prop2' := integer(),
            _ => _},
          binary() | maybe_improper_list()) ->
             'ok'

Answer 1

首先，我看不到任何elixir typespec教程，在这些教程中他们在规范中使用变量名编写@spec；相反，我发现的都是在typespec中仅具有类型的教程：

@spec calculate(arg1 :: String.t, arg2 :: CustomType.t, arg3 :: String.t)

v.

@spec calculate(String.t, CustomType.t, String.t)

尽管如此，以下内容还是通过了我的透析器：

defmodule CustomType do
  @type t :: %CustomType{}
  defstruct a: nil, b: nil
end

defmodule MyModule do

  @spec calculate(arg1::String.t, arg2::CustomType.t, arg3::String.t) :: number

  #def calculate(<<arg1::binary>>, %CustomType{} = arg2, <<arg3::binary>>) do
  def calculate(arg1, %CustomType{} = arg2, arg3) when is_binary(arg1) and is_binary(arg3) do
    calculate(arg1, arg2, [arg3])
  end

  @spec calculate(String.t, CustomType.t, maybe_improper_list()) :: number

  def calculate(<<arg1::binary>>, %CustomType{} = arg2, arg3) when is_list(arg3) do
    123
  end

end

~/elixir_programs/friends$ mix dialyzer
Compiling 1 file (.ex)
warning: variable "arg1" is unused (if the variable is not meant to be used, prefix it with an underscore)
  lib/friends/my_module.ex:17

warning: variable "arg2" is unused (if the variable is not meant to be used, prefix it with an underscore)
  lib/friends/my_module.ex:17

Checking PLT...
[:compiler, :connection, :crypto, :db_connection, :decimal, :ecto, :elixir,
 :kernel, :logger, :poolboy, :postgrex, :stdlib]
PLT is up to date!
Starting Dialyzer
dialyzer args: [
  check_plt: false,
  init_plt: '/Users/7stud/elixir_programs/friends/_build/dev/dialyxir_erlang-20.3_elixir-1.8.2_deps-dev.plt',
  files_rec: ['/Users/7stud/elixir_programs/friends/_build/dev/lib/friends/ebin'],
  warnings: [:unknown]
]
done in 0m1.43s
done (passed successfully)

我会说我找到这种语法：

@spec calculate(String.t, CustomType.t, String.t)

更容易阅读。

根据Learn You Some Erlang：

is a subtype of the success typing
这会警告您，实际上，您的规范对于您的代码应接受什么并告诉您（尽管间接）您应该做出类型说明放松，或在功能上更好地验证您的输入和输出反映类型规范。

但是，我无法生成您的透析器输出：

defmodule CustomType do
  @type t :: %CustomType{}
  defstruct a: nil, b: nil
end

defmodule MyModule do

  @spec calculate(arg1 :: String.t, 
                  arg2 :: CustomType.t, 
                  arg3 :: String.t) 
  :: :ok | :error

  def calculate(arg1, %CustomType{} = arg2, arg3) 
  when is_binary(arg1) and is_binary(arg3) do
    calculate(arg1, arg2, [arg3])
  end

  @spec calculate(arg1 :: String.t, 
                  arg2 :: CustomType.t, 
                  arg3 :: maybe_improper_list()) 
  :: :ok | :error

  def calculate(arg1, %CustomType{} = arg2, arg3) 
  when is_binary(arg1) and is_list(arg3) do
    case arg1 do
      "hello" -> :ok
      "goodbye"  -> :error
    end
  end

end

$ mix dialyzer
Compiling 1 file (.ex)
warning: variable "arg2" is unused (if the variable is not meant to be used, prefix it with an underscore)
  lib/friends/my_module.ex:19

Checking PLT...
[:compiler, :connection, :crypto, :db_connection, :decimal, :ecto, :elixir,
 :kernel, :logger, :poolboy, :postgrex, :stdlib]
PLT is up to date!
Starting Dialyzer
dialyzer args: [
  check_plt: false,
  init_plt: '/Users/7stud/elixir_programs/friends/_build/dev/dialyxir_erlang-20.3_elixir-1.8.2_deps-dev.plt',
  files_rec: ['/Users/7stud/elixir_programs/friends/_build/dev/lib/friends/ebin'],
  warnings: [:unknown]
]
done in 0m1.46s
done (passed successfully)

因此，您需要发布一个最小的示例来复制您的透析器输出。我将注意到arg3必须在第一个子句中为二进制，因此当您在第一个子句的正文中调用calculate(arg1, arg2, [arg3])时，参数[arg3]永远不会是不正确的列表，因此您可以收紧该规范直到：list(binary)（第二个子句）。

============

这是我编写的代码：

defmodule CustomType do
  @type t :: %CustomType {
    prop1: String.t(),
    prop2: integer(),
    prop3: String.t(),
    prop4: boolean()
  }

  defstruct prop1: nil, prop2: nil, prop3: nil, prop4: nil
end

defmodule MyModule do
  @spec calculate(arg1 :: String.t, 
                  arg2 :: CustomType.t, 
                  arg3 :: String.t) 
  :: :ok | :error

  def calculate(arg1, %CustomType{} = arg2, arg3) 
  when is_binary(arg1) and is_binary(arg3) do
    calculate(arg1, arg2, [arg3])
  end

  @spec calculate(arg1 :: String.t, 
                  arg2 :: CustomType.t, 
                  arg3 :: maybe_improper_list) 
  :: :ok | :error

  def calculate(arg1, %CustomType{prop1: val, prop2: val2}, arg3) 
  when is_binary(arg1) and is_binary(val) and is_integer(val2) and is_list(arg3) do
    case arg1 do
      "hello" -> :ok
      "goodbye"  -> :error
    end
  end

end

正在运行的透析器：

~/elixir_programs/friends$ mix dialyzer 
Checking PLT... [:artificery,  
 :compiler, :connection, :crypto, :db_connection, :decimal,  :distillery,  
 :ecto, :elixir, :kernel, :logger, :poolboy, :postgrex,  :runtime_tools,  
 :stdlib] Finding suitable PLTs Looking up modules in dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt Finding applications for dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt Finding modules for dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt Checking 718 modules in dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt Adding 56 modules to dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt Starting Dialyzer dialyzer args: [   
  check_plt: false,   
init_plt: '/Users/7stud/elixir_programs/friends/_build/dev/dialyxir_erlang-  
20.3_elixir-1.8.2_deps-dev.plt', files_rec:   
['/Users/7stud/elixir_programs/friends/_build/dev/lib/friends/ebin'],  
  warnings: [:unknown] ] done in 0m1.26s done (passed successfully)

mix.exs中包含以下内容：

  def project do
    [
      app: :friends,
      version: "0.1.0",
      elixir: "~> 1.6",
      start_permanent: Mix.env() == :prod,
      deps: deps(),
      dialyzer: [
            flags: ~w[underspecs 
                      overspecs 
                      race_conditions
                      error_handling 
                      unmatched_returns]a
      ]
    ]
  end

以下是输出：

~/elixir_programs/friends$ mix dialyzer
Checking PLT...
[:artificery, :compiler, :connection, :crypto, :db_connection, :decimal,  
:distillery, :ecto, :elixir, :kernel, :logger, :poolboy, :postgrex,  
:runtime_tools, :stdlib]  
PLT is up to date!  
Starting Dialyzer  
dialyzer args: [
  check_plt: false,
  init_plt: '/Users/7stud/elixir_programs/friends/_build/dev/dialyxir_erlang-20.3_elixir-1.8.2_deps-dev.plt',
  files_rec: ['/Users/7stud/elixir_programs/friends/_build/dev/lib/friends/ebin'],
  warnings: [:underspecs, :overspecs, :race_conditions, :error_handling,
   :unmatched_returns, :unknown]
]
done in 0m1.38s  
done (passed successfully)

Dialyzer发出Type规范是具有相同名称的多个功能成功键入的子类型

1 个答案: