Object model
The decorators are useful for commands that are simple and follow basic CLI conventions. Sometimes you want to extend your CLI with custom features. This is where the object model comes in.
Each concept in a commandline program is represented by an object in the
dryparse.objects module. Thus, each command is represented by an
instance of Command, each option by an
Option, etc.
The fundamentals
The simplest way to create a command is:
git = Command("git", desc="A version control software")
Adding options is super easy:
git.paginate = Option("-p", "--paginate")
Note
The git.paginate attribute didn’t exist before. We created it dynamically by assigning a value to it.
By default, options have a type of bool. This means that when the option is
specified on the command line it will have a value of True, and False
otherwise.
Let’s create an option of type int:
git.retries = Option("-r", "--retries", type=int)
This option will expect an argument to be specified via the command line. The
argument is automatically converted to the type we specified (in this case
int).
Note
All options except for bool and some special types
take CLI arguments, and those arguments are automatically converted to the
specified type.
Note that commands include a --help option by default, via a help
attribute that is just like any other attribute. You can delete it if you don’t need it:
del git.help
Adding a subcommand
Adding a subcommand is just as easy as adding an option:
Defining positional arguments
git.add.args = Arguments([])
These use cases are simple, but Arguments has so much
more to offer. Take a look at its API documentation.
Root command
CLI programs usually include a --version option in their root command. While
you can add this option yourself, we provide RootCommand as a convenience:
git = RootCommand("git", version="0.1.0", desc="A version control software")