VURF

Viliam's Universal Requirements Format

What it is

VURF is a format, parser, CLI, and python module for saving packages into Python-ish looking file. It supports different sections, conditionals and deep nesting and envaluation thanks to AST parser.

Example packages.vurf

with pip:
  vurf
  black
  click==8.0.0
  if at_work:
    ql-cq
    ql-orange
with brew:
  nnn  # terminal file manager

Installation

pip install vurf

Usage

# Do something to initialize config and packages files
$ vurf default

# Basic operations
$ vurf add some-package
$ vurf remove package

# Print packages
$ vurf packages

# Install them
$ vurf install

For all options look at CLI section and for integration with other tools look at Automation.

CLI

$ vurf
Usage: vurf [OPTIONS] COMMAND [ARGS]...

Options:
  -q, --quiet  Don't produce unnecessary output.
  --version    Show the version and exit.
  --help       Show this message and exit.

Commands:
  add              Add package(s).
  config           Edit config file.
  default          Print default section.
  edit             Edit packages file.
  format           Format packages file.
  has              Exit with indication if package is in packages.
  has-section      Exit with indication if section is in sections.
  install          Install packages.
  package-section  Print the first section that contains the package.
  packages         Print list of packages.
  print            Print contents of packages file.
  remove           Remove package(s).
  sections         Print list of sections.
  uninstall        Uninstall packages.

Completions

Shell completions are installed into vurf_completions in your side-packages. The easiest way to find the location is to run pip show -f vurf | grep Location.

Then you can source them for example like this

# .bashrc
source "/Users/viliam/Library/Python/3.10/lib/python/site-packages/vurf_completions/completions.bash"

Config

Note: VURF will automatically create config file on the first run.

Config file format

# Where packages file is saved
packages_location = "/Users/viliam/packages.vurf"
# Name of the default section
default_section = "brew"

# Sections can be though of as installers for different packages
# `install` and `uninstall` attributes are optional and default to `echo`
# `sequential` attribute is optional and defaults to `false`
# Use `sequential = true` if you want to install/uninstall packages one by one
[[sections]]
name = "brew"
install = "brew install"
uninstall = "brew uninstall"
sequential = false

[[sections]]
name = "cask"
install = "brew install --cask"

[[sections]]
name = "python"
install = "pip install --quiet --user"
uninstall = "pip uninstall"

# Parameters are constants that can be accessed from conditionals
[parameters]
hostname = "mac"
primary_computer = true
fs = "apfs"

Grammar

VURF has grammar and LALR(1) parser implemented in Lark. The "source code" aims to look like Python code as much as possible.

Keywords

• with [section] - specifies "section" of requirements file. Different sections usually have different installers.
• if [condition]: - conditions for including packages. See Conditionals sections.
• elif [condition]:
• else:
• ... - ellipsis - placeholder for empty section.

Packages

• are saved as [name] # [comment]
• name can be almost any valid package name (cannot start with "." or contain tabs or newline characters)
• names containing spaces must be quoted. E.g. 'multi word package name'
• comments are optional

Conditionals

Conditionals are evaluated using Python's eval function. They can be as simple as

if var:
  ...

or as complex as

if pathlib.Path('some-file').exists() and os.lstat('some-file').st_mode == 33188:
  ...

Evaluation has access to standard library modules:

• os
• pathlib
• subprocess

and also to configuration variables defined in config.toml.

Module

VURF provides python module that exposes approximately the same API as the CLI.

Example

from vurf import Vurf

with Vurf.context() as packages:
    sections = packages.sections()
    packages.add('some-package', section = sections[1])
    assert packages.has('some-package')
    packages.remove(['other-package', 'third-package'])