Tutorial by Topics: lex



The Flexible Box module, or just 'flexbox' for short, is a box model designed for user interfaces, and it allows users to align and distribute space among items in a container such that elements behave predictably when the page layout must accommodate different, unknown screen sizes. A flex container expands items to fill available space and shrinks them to prevent overflow.

The Actions class gives us a way of emulating precisely how a user would interact with a web page/elements. Using an instance of this class you can describe a series of actions, such as clicking, double-clicking, dragging, pressing keys, etc. Once these actions are described, in order to carry the actions out, you must call must build the actions (.Build()) and then instruct them to be performed (.Perform()). So we must describe, build, perform. The examples below will expand upon this.

IO may be blocking/non-blocking and synchronous/asynchronous. POSIX API provides synchronous blocking API (e.g. classic read, write, send, recv calls), synchronous non-blocking API (same functions, file descriptors opened with O_NONBLOCK flag and IO-multiplexing calls) and asynchonous API (functions starting with aio_).

Synchronous API is usually used with "one thread/process per fd" style. This is dreadful for resources. Non-blocking API allows to operate with a set of fds in one thread.

When creating a performant and data-driven application, it can be very helpful to complete time-intensive tasks in an asynchronous manner and to have multiple tasks running concurrently. This topic will introduce the concept of using ThreadPoolExecutors to complete multiple ansynchronous tasks concurrently.


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