Question

我得到＆＃34; Elixir编译错误：带有多个子句和默认值的定义需要标题。＆＃34;对于以下功能。我不明白我为什么会错误地收到这个错误？关于如何解决它的任何建议？

#import "LoadPresentViewController.h"
#import "WebViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (IBAction)doLoadPresent:(id)sender {

    WebViewController *wvc = [[WebViewController alloc]init];
    [self presentViewController:wvc animated:NO completion:nil];

}


- (void)viewDidLoad {
    [super viewDidLoad];

    // this fails in viewDidLoad
//  WebViewController *wvc = [[WebViewController alloc]init];
//  [self presentViewController:wvc animated:NO completion:nil];

}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    // this succeeds in viewDidAppear
    WebViewController *wvc = [[WebViewController alloc]init];
    [self presentViewController:wvc animated:NO completion:nil];

}

@end

错误讯息：

  def stream(query, opts \\ []) do
    initial_key = Keyword.get(opts, :initial_key, 0)
    key_name = Keyword.get(opts, :key_name, :id)
    chunk_size = Keyword.get(opts, :chunk_size, 500)

    Stream.resource(fn -> {query, initial_key} end,
      fn {query, last_seen_key} ->
        results = query
          |> Ecto.Query.where([r], field(r, ^key_name) > ^last_seen_key)
          |> Ecto.Query.limit(^chunk_size) 
          |> __ENV__.module.all

        case List.last(results) do
          %{^key_name => last_key} ->
            {results, {query, last_key}}
          nil ->
            {:halt, {query, last_seen_key}}
        end
      end,
      fn _ -> [] end)
  end

Answer 1

当你stream/2时，Ecto已经定义了一个名为use Ecto.Repo, otp_app: :my_app的函数。你将需要将你的功能称为别的东西。

Elixir编译错误：具有多个子句和默认值的定义需要标头

1 个答案: