2 :ID: 46115263-ed3d-4acc-9ec5-523d7acf87b8
4 #+TITLE: Commandline interface arguments processing
5 #+AUTHOR: Svjatoslav Agejenko
8 - [[id:bb4f96cd-458c-495b-a605-313b2e3e28d2][Back to CLI Helper - library main page]]
11 ** Commands and Arguments
13 Every command-line application has a way of receiving input from
14 users, usually in the form of command-line arguments. A command-line
15 argument is a piece of information provided to the command-line
16 application when it's invoked. These arguments are provided as an
17 array of strings. The first element of the array (argument 0) is
18 typically the name of the command itself.
20 In the example below, 'my-video-coder' is our command, and the rest
24 my-video-coder encode --input vid1.mp4 vid2.mp4 vid3.mp4 --quality 5
27 To better understand how these concepts work together, let's break
28 down our example command:
30 | argument # | value(s) | type |
31 |------------+----------------------------+-------------------------------|
32 | 0 | my-video-coder | command |
33 | 1 | encode | [[id:94242e8a-c59b-42fd-8cc7-ba3df1938119][subcommand]] |
34 | 2 | --input | [[id:ffedf388-4d23-41eb-98d0-83fd3940b24d][option1]] |
35 | 3, 4, 5 | vid1.mp4 vid2.mp4 vid3.mp4 | [[id:8a39d20c-421f-4bc7-94e4-8e561e58bea0][parameters for --input option]] |
36 | 6 | --quality | [[id:ffedf388-4d23-41eb-98d0-83fd3940b24d][option2]] |
37 | 7 | 5 | [[id:8a39d20c-421f-4bc7-94e4-8e561e58bea0][option for --quaily option]] |
41 :ID: 94242e8a-c59b-42fd-8cc7-ba3df1938119
44 Subcommands are more specific actions that a command can perform. They
45 are often used with commands that have multiple functions. In our
46 example, *encode* is a subcommand of *my-video-coder*.
50 :ID: ffedf388-4d23-41eb-98d0-83fd3940b24d
53 Options are arguments that change the behavior of a command or
54 subcommand. They usually start with a dash (-) or double dash
55 (--). For instance, *--input* and *--quality* are options in our
60 :ID: 8a39d20c-421f-4bc7-94e4-8e561e58bea0
63 Parameter provides additional information to a command, subcommand or
66 For instance, in our example:
67 - 'vid1.mp4 vid2.mp4 vid3.mp4' are parameters for the *--input* option.
68 - '5' is a parameter for the *--quality* option.
70 * Implementation :noexport:
72 Parsing Command-line Arguments:
73 - `Parameter` class is used for defining parameters with their
74 descriptions, types, and aliases. It also keeps track of whether the
75 specific option was present in the command line or not. This
76 information is used later in the processing.
78 - `DirectoryParameter`, `FileParameter`, `IntegerParameter`,
79 `StringParameter`, `NullParameter`, and `StringParameters` are
80 examples of Parameter classes, each one having unique
81 characteristics for handling specific types of parameters
82 (directories, files, integers, strings, etc.).
84 - `ArgumentCount` class determines if a option can have any amount
85 of arguments (MULTI), exactly one argument (SINGLE), or no arguments
88 - `Parser` class takes all these parameters and checks whether all
89 required arguments are provided and if they match the expected