Scripting with Paver-Command Definition

Paver is a library for easily creating command line tools in Python.

You can easily create command line tools to some extent using Python's standard library such as `ʻargparse``, but Paver makes it much easier to create scripts with subcommands in particular. ..

The Paver original documentation focuses on automating Python packaging, so I'd like to explain it as a task definition and execution tool.

setup

$ easy_install paver

Make a task

If you create a file called pavement.py and then create a function with a decorator called @ task, it becomes a task.

pavement.py

from paver.easy import *

@task
def hello():
    """My first task."""
    print 'hello'

To run the task, run paver task name.

$ paver hello
---> pavement.hello
hello

paver -h also shows the tasks you have defined. docstrin is the description for that command.

$ paver -h
---> paver.tasks.help
Usage: paver [global options] taskname [task options] [taskname [taskoptions]]

Options:
  --version             show program's version number and exit
  -n, --dry-run         don't actually do anything
…
Tasks from pavement:
  hello          - My first task.

Take an argument

To take an argument, add the decorator @consume_args to the function that defines the task and write the argument ```args``.

pavement.py

from paver.easy import *

@task
@consume_args
def hello(args):
    """My first task."""
    print 'hello', args

$ paver hello foo bar
---> pavement.hello
hello ['foo', 'bar']

Define options

Use the @cmdopts decorator to define options, and the argument ```optionsto receive them. Pass the @cmdoptsdecorator as an argument a list of options defined in tuples in the form (long name, one letter, help) . Adding to the end of a long name gives you the option to take an argument.

pavement.py

from paver.easy import *

@task
@cmdopts([
    ('foo', 'f', "The foo"), # -f or--foo
    ('bar=', 'b', "Bar bar bar"), # -b xxx or--bar=xxx
    ])
def hello(options):
    """My first task."""
    print 'hello', options.foo, options.bar

$ paver hello --foo -b 3
---> pavement.hello
hello True 3

Actually, ```optionsis defined as a global variable of paver.easyeven if it is not taken as an argument, so if you do from paver.easy import * ``, you do not have to take an argument. Can also be used.

pavement.py

from paver.easy import *

@task
@cmdopts([
    ('foo', 'f', "The foo"),
    ('bar=', 'b', "Bar bar bar"),
    ])
def hello():
    """My first task."""
    print 'hello', options.foo, options.bar