pyworkdir

Python working directories

Quickstart

conda install -c conda-forge pyworkdir

Basic Usage

from pyworkdir import WorkDir

with WorkDir("some_directory"):
    # everything in this context is run 
    # in the specified directory
    pass 

Directories are Customizable Classes

WorkDir classes can be be customized by adding a file workdir.py to the directory. All variables, functions, or classes defined in this file will be added as attributes of the WorkDir instances.

For instance, consider the following workdir.py file:

# -- workdir.py --
def data_file(workdir, filename="data.csv"):
    return workdir/filename

The function can now be accessed from other code as follows:

from pyworkdir import WorkDir

with WorkDir() as wd:
    print(wd.data_file())

Note that the parameter workdir behaves like the self argument of the method. If workdir is not an argument of the function, the function behaves like a static method.

By default, the WorkDir instance also recursively inherits attributes defined in its parent directory's workdir.py files. Therefore, subdirectories behave like subclasses.

Directories have a Command Line Interface

Custom functions of the WorkDir are directly accessible from a terminal via the command workdir. Before being called from the command line, all function parameters (except the reserved keywords workdir and here) have to be declared as Click options.

# -- workdir.py --
import click

num_apples = 2

@click.option("-c", type=int, default=12, help="A number (default:12)")
@click.option("-s","--somebody", type=str, help="A name")
def hello(count, somebody, workdir):
    """This function says hello."""
    workdir.num_apples += 1
    print(
        f"{count} times Hello! to {somebody}: "
        f"we have {workdir.num_apples} apples."
    )

Calling the function from the command line looks like this:

foo@bar:~$  workdir hello --help
Usage: workdir hello [OPTIONS]

  This function says hello.

Options:
  -c, --count INTEGER  A number (default:12)
  -s, --somebody TEXT  A name
  --help               Show this message and exit.


foo@bar:~$ workdir hello -s "you"
12 times Hello! to you: we have 3 apples.

Writing workdir.py files like this makes it easy to define local functions that can be called both from inside python and from a terminal. For the latter, the workdir.py behaves similar to a Makefile.

To suppress generation of the command line interface for a function, pyworkdir provides a no_cli decorator.

    # -- workdir.py --

    from pyworkdir import no_cli

    @no_cli
    def a_function_without_command_line_interface():
        pass

Changing Environment Variables

from pyworkdir import WorkDir

with WorkDir(environment={"MY_ENVIRONMENT_VARIABLE":"1"}):
    # in this context the environment variable is set
    pass

# outside the context, it is not set any longer

Yaml Files

Environment variables and simple attributes can also be set through yml files. The templates {{ workdir }} and {{ here }} are available and will be replaced by the working directory instance and the directory that contains the yml file, respectively.

# -- workdir.yml --
environment:
    VAR_ONE: "a"
attributes:
    my_number: 1
    my_list:
        - 1
        - 2
        - 3
    my_tmpdir: {{ here/"tmpdir" }}
    my_local_tmpfile: {{ workdir/"file.tmp" }}
commands:
    echo: echo Hello // print Hello to the command line

The commands are shortcuts for terminal commands that can be called from python and from the command line. Everything after // is used as a documentation string for the command line interface. The attributes and environment variables get added to the WorkDir.

from pyworkdir import WorkDir
with WorkDir() as wd:
    print(wd.my_number + 5, wd.my_tmpdir , wd.my_local_tmpfile)
    for el in wd.my_list:
        print(el)
    print(os.environ["VAR_ONE"])

Note that environment variables passed to the constructor have preference over those in a yml file.

Logging

from pyworkdir import WorkDir
import logging

wd = WorkDir()
wd.log("a INFO-level message")
wd.log("a DEBUG-level message", logging.DEBUG)

By default, INFO-level and higher is printed to the console. DEBUG-level output is only printed to a file workdir.log.

Documentation

Copyright

Copyright (c) 2019, Andreas Krämer

Acknowledgements

External Packages:

• Click - Command line interface
• Jinja2 - Template engine
• PyYaml - Yaml parser

Project based on the Computational Molecular Science Python Cookiecutter version 1.0.