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This article focuses on "how to use the Python command line library fire", interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to use the Python command line library fire.

I. Preface

The fire to be introduced today is to play with the command line in a generalized object-oriented way, which can be classes, functions, dictionaries, lists, etc., which is more flexible and simpler.

This series of articles use Python 3 as the interpreter by default. If you are still using Python 2, please pay attention to the differences in syntax and library use between them.

II. Introduction

Fire can automatically generate a command line interface from any Python object. It has the following features:

Can generate CLI in a simple way

Is a utility for developing and debugging Python code

Ability to convert existing code or someone else's code to CLI

Makes it easier to convert between Bash and Python

Make it easier to use REPL by pre-setting the required modules and variables for REPL

You can quickly install the fire library with the following command:

Pip install fire

III. Get started quickly

Recall the steps to implement a command line program using argparse, docopt, and click:

For argparse, first set up the parser, then define parameters, then parse the command line, and finally implement the business logic (four steps)

For docopt, first define the interface description, then parse the command line, and finally implement the business logic (three steps)

For click, it is to implement the business logic and define parameters through the decorator (two steps)

Their implementation steps are getting simpler and simpler, from four steps to two steps. But today's protagonist fire only needs one step, the present business logic is enough.

It's incredibly simple. Why is that enough? We might as well consider the function in Python, whether the function can correspond to a command line program, and the parameters of the function can correspond to the parameters and options of the command line program? Look at the class in Python, whether a class can correspond to a command line program, and each instance method in the class can correspond to a subcommand, and the parameters in the instance method are the parameters and options of the corresponding subcommand.

Come to think of it, it's possible to use the following example to see how fire allows us to implement command-line programs in a simple way.

3.1 use function

Let's take a look at this example:

Import firedef hello (name= "World"): return 'Hello {name}!' .format (name=name) if _ _ name__ ='_ _ main__': fire.Fire (hello)

In the above example, a hello function is defined that accepts the name parameter and has a default value of "World". The command function can be implemented very easily and quickly using fire.Fire (hello). The command line accepts the-- name option, uses the default value "World" when it is not provided, and follows the value provided when it is provided.

You can execute the following commands on the command line:

$python hello.pyHello Worldwide $python hello.py-- name=ProdesireHello Productivity repayment $python hello.py-- helpINFO: Showing help with the command 'hello.py-help'.NAME hello.pySYNOPSIS hello.py FLAGS-- name=NAME

3.2 use classes

Using functions is the easiest way, and fire also supports it if we want to implement it in a more organized way, such as using classes.

Import fireclass Calculator (object): "A simple calculator class." Def double (self, number): return 2 * number def triple (self, number): return 3 * numberif _ _ name__ ='_ _ main__': fire.Fire (Calculator)

In the above example, a Calculator class is defined, which has two instance methods double and triple, and both accept the number parameter with no default value. The command function can be easily and quickly implemented using fire.Fire (Calculator). This command line supports two subcommands, double and triple, the position parameter NUMBER or the option parameter-- number.

You can execute the following commands on the command line:

$python calculator.py double 1020$ python calculator.py triple-- number=1545$ python calculator.py double-- helpINFO: Showing help with the command 'calculator.py double-help'.NAME calculator.py doubleSYNOPSIS calculator.py double NUMBERPOSITIONAL ARGUMENTS NUMBERNOTES You can also use flags syntax for POSITIONAL ARGUMENTS here, I believe you have a better understanding of "how to use the Python command line library fire", you might as well do it in practice! Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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