chaining | 易学教程

Can this promise nesting be changed to chaining?

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问题 This is the pseudo scenario | then (items) | then (items, actions) getItems() | getActions(for:items) | apply(actions -> items) :promise | :promise | model <= items | | :synchronous So in words: I need to get a list of global items. Fine. Items fetched. Make a request for actions that user has taken over previously fetched items. Fine. Actions fetched. Apply actions to items list. Put items on the model and display in view. This is somewhat the code I'm using return itemsResource .getItems

How to use chaining in dplyr to access “internal” variables

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问题 New to (d)plyr, working through chaining, a basic question - for the hflights example, want to use one of these embedded vars to make a basic plot: hflights %>% group_by(Year, Month, DayofMonth) %>% select(Year:DayofMonth, ArrDelay, DepDelay) %>% summarise( arr = mean(ArrDelay, na.rm = TRUE), dep = mean(DepDelay, na.rm = TRUE) ) %>% plot (Month, arr) Returns: Error in match.fun(panel) : object 'arr' not found I can make this work going step by step, but can I get where I want to go somehow

Ruby Method Chaining

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问题 I would like to chain my own methods in Ruby. Instead of writing ruby methods and using them like this: def percentage_to_i(percentage) percentage.chomp('%') percentage.to_i end percentage = "75%" percentage_to_i(percentage) => 75 I would like to use it like this: percentage = "75%" percentage.percentage_to_i => 75 How can I achieve this? 回答1: You have to add the method to the String class: class String def percentage_to_i self.chomp('%') self.to_i end end With this you can get your desired

Method chaining

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问题 class A { public function model($name) { if (file_exists($name.'.php')) { require $name.'.php'; $this->$name = new $name(); } } } class C extends A { function __construct() { $this->load = $this; $this->load->model('test'); $this->test->say(); } } $Controller = new C(); I want to create a simple code igniter like loader class. Is there a proper way for doing this technique? 回答1: You would use Fluent Interface pattern. <?php class Employee { public $name; public $surName; public $salary;

Android IsoDep command chaining failure

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问题 I am making a NFC application that use ISO-DEP (ISO 14443-4) as TagTechnology. I try to execute a authentication with a DESFire EV1. The authentication work well if the chaining of the command is without pause. But if for exemple, I make something that take time (like the Thread.Sleep after NATIVE_AUTHENTICATION_COMMAND_P1) I got an error 0x911C ("Command code not supported") during the authentication command part 2 from the card. Normaly the error come when the authentication has been

How to chain async methods in javascript ES6 classes

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问题 I want to chain methods from a class. I have o problems with synchronous methods, but I don't know how to do it with asynchronous methods. For example, this class: class Example { constructor() { this.val = 0 } async () { setTimeout(() => { this.val += 1 return this }, 5000) } sync () { this.val += 1 return this } check () { console.log('checker', this.val) return this } } This works: new Example().sync().check() > 1 But this doesn't work: new Example().async().check() > TypeError: Cannot

Chain function call after function definition [duplicate]

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问题 This question already has answers here : Ember computed properties in Coffeescript (3 answers) Closed 6 years ago . How can I chain a function call after a function definition in CoffeeScript? Equivalent javascript would be: var foo = function () { // stuff }.bar() The only way I managed to do it is: foo = `function () { // stuff }.bar()` But I hope for a better solution than embedding javascript in my (beautiful) coffeescript code 回答1: Try like this: foo = (-> stuff).bar() For example:

method chaining including class constructor

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问题 I'm trying to implement method chaining in C++, which turns out to be quite easy if the constructor call of a class is a separate statement, e.g: Foo foo; foo.bar().baz(); But as soon as the constructor call becomes part of the method chain, the compiler complains about expecting ";" in place of "." immediately after the constructor call: Foo foo().bar().baz(); I'm wondering now if this is actually possible in C++. Here is my test class: class Foo { public: Foo() { } Foo& bar() { return *this

jQuery chaining and cascading then's and when's

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I currently have a humongous if-then-else loop in front of me which first gets multiple cantinas from a webservice. Then it gets all available meals (for each menu) and all available side dishes (for each menu). For each of the meals as well as the sides it then checks for all additives and aggregates them. In the end I have multiple menus with meals, side dishes and all their additives. The following flowchart shows the process: I want to beautify the code and want to make use of promises with jQuery - but I can't figure out how to do it as I have to stack a then after a when (at least I

How to do method chaining with DOMDocument?

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问题 Do method chaining with PHP is easy. But I need something like this, $xml = $dom->transformToThis('file1.xsl')->transformToThis('file2.xsl')->saveXML(); or $books = $dom-> transformToThis('file1.xsl')-> transformToThis('file2.xsl')-> getElementsByTagName('book'); It is possible with PHP's DOMDocument or DOMNode? class DOMxx extends DOMDocument { public function __construct() { parent::__construct("1.0", "UTF-8"); } function trasformToThis($xslfile) { $xsldom = new DOMDocument('1.0', 'UTF-8');