Question

关于我在本教程中看到的几种方法的问题：https://richonrails.com/articles/rails-presenters

特别是：

module ApplicationHelper
    def present(model, presenter_class=nil)
        klass = presenter_class || "#{model.class}Presenter".constantize
        presenter = klass.new(model, self)
        yield(presenter) if block_given?
    end
end

和

class BasePresenter < SimpleDelegator 
    def initialize(model, view)
        @model, @view = model, view
        super(@model)
    end

    def h 
        @view 
    end

end

present方法如何运作？我对其参数参数感到困惑，即model, presenter_class=nil以及整个方法。

我也对model, view个参数非常困惑，以及super(@model)方法在哪里/什么？

任何可以解释这些方法的信息都会非常有用，因为我一直盯着它过去，同时想知道它们是如何起作用的。

Answer 1

我会试一试。

present方法接受两个参数，一个模型和一个presenter类。

presenter_class = nil表示presenter_class是可选参数，如果在调用方法时未将该变量作为参数传递，则nil将设置为# Define the Helper (Available in all Views) module ApplicationHelper # Define the present method, accepts two parameters, presnter_class is optional def present(model, presenter_class=nil) # Set the presenter class that was passed in OR attempt to set a class that has the name of ModelPresenter where Model is the class name of the model variable klass = presenter_class || "#{model.class}Presenter".constantize # ModelPresenter is initialized by passing the model, and the ApplicationHelper class presenter = klass.new(model, self) # yeild the presenter if the rails method block_given? yield(presenter) if block_given? end end。

我已经在代码中添加了评论，以便逐步解释发生了什么。

BasePresenter

Here's another question explaining how yield works

Here's some more info on the rails constantize method

class BasePresenter < SimpleDelegator def initialize(model, view) # Set the instance variables @model and @view as the two parameters passed to BasePresenter.new @model, @view = model, view # calls the inherited SimpleDelegator initializer with the @model parameter super(@model) end # An instance method that returns the @view variable that was set on initialization def h @view end end继承自SimpleDelegator类(documentation)。

@interface NSString (ObjCFlagTesting)
-(void) myLibName_TestLinkerFlag;
@end

@implementation NSString (ObjCFlagTesting)
-(void) myLibName_TestLinkerFlag {}
@end

Rails演示者教程中的方法问题

1 个答案: