Rxpy 简明教程

RxPY - Working With Observables

一个可观察对象是一个创建观察员并将其附加到预期值源（例如点击、DOM 元素上的鼠标事件等）的函数。

An observable, is a function that creates an observer and attaches it to the source where values are expected, for example, clicks, mouse events from a dom element, etc.

下面提及的主题将在本章中详细研究。

The topics mentioned below will be studied in detail in this chapter.

Create Observables
Subscribe and Execute an Observable

Create observables

要创建一个可观察对象，我们将使用 {}s0 方法并向其传递一个包含以下项的函数。

To create an observable we will use create() method and pass the function to it that has the following items.

on_next() − This function gets called when the Observable emits an item.
on_completed() − This function gets called when the Observable is complete.
on_error() − This function gets called when an error occurs on the Observable.

要使用 create() 方法，首先按下方所示导入该方法−

To work with create() method first import the method as shown below −

from rx import create

以下是创建一个 observable 的工作示例−

Here is a working example, to create an observable −

testrx.py

from rx import create
deftest_observable(observer, scheduler):
   observer.on_next("Hello")
   observer.on_error("Error")
   observer.on_completed()
source = create(test_observable).

Subscribe and Execute an Observable

要订阅一个 observable，我们需要使用 subscribe() 函数，并传递回调函数 on_next、on_error 和 on_completed。

To subscribe to an observable, we need to use subscribe() function and pass the callback function on_next, on_error and on_completed.

以下是工作示例−

Here is a working example −

testrx.py

from rx import create
deftest_observable(observer, scheduler):
   observer.on_next("Hello")
   observer.on_completed()
source = create(test_observable)
source.subscribe(
   on_next = lambda i: print("Got - {0}".format(i)),
   on_error = lambda e: print("Error : {0}".format(e)),
   on_completed = lambda: print("Job Done!"),
)

subscribe() 方法负责执行 observable。回调函数 on_next 、 on_error 和 on_completed 必须传递给 subscribe 方法。随后对 subscribe 方法的调用将执行 test_observable() 函数。

The subscribe() method takes care of executing the observable. The callback function on_next, on_error and on_completed has to be passed to the subscribe method. Call to subscribe method, in turn, executes the test_observable() function.

不必将所有三个回调函数都传递给 subscribe() 方法。您可以根据自己的需要传递 on_next()、on_error() 和 on_completed()。

It is not mandatory to pass all three callback functions to the subscribe() method. You can pass as per your requirements the on_next(), on_error() and on_completed().

lambda 函数用于 on_next、on_error 和 on_completed。它将采用参数并执行给定的表达式。

The lambda function is used for on_next, on_error and on_completed. It will take in the arguments and execute the expression given.

以下是创建的 observable 的输出−

Here is the output, of the observable created −

E:\pyrx>python testrx.py
Got - Hello
Job Done!