JnyJny/cli-examples

A selection of CLI example code in Python

cli-examples - Selection of Python CLI Implementations

Installation

Clone The Repo

1. $ git clone https://github.com/JnyJny/cli-examples
2. $ cd cli-examples

Install with Poetry

1. $ poetry shell
2. $ poetry install

Install with Pip

1. $ python3 -m venv .venv
2. $ source .venv/bin/activate
3. $ python3 -m pip install -r requirements.txt

---

Introduction to sys.argv

The contents of cli/00-dump-argv/__main__.py:

""" introduction to sys.argv

Prints the contents of sys.argv and exits with status 11
"""

import sys

if __name__ == "__main__":
    for n, item in enumerate(sys.argv):
        print(f"argv[{n}] == {item}")
    exit(11)

$ python3 -m cli.00-dump-argv foo -b baz -a --ack
argv[0] == /Users/ejo/local/cli-examples/cli/00-dump-argv/__main__.py
argv[1] == foo
argv[2] == -b
argv[3] == baz
argv[4] == -a
argv[5] == --ack

---

Implementation of cp parsing sys.argv

The contents of cli/10-argv/__main__.py:

""" copy file implemented with sys.argv
"""

import sys

if __name__ == "__main__":
    # default values
    inputfile = sys.stdin
    outputfile = sys.stdout
    flag = False

    # sys.argv[0] is the name of the program
    for ndx, item in enumerate(sys.argv[1:]):
        if item in ["-i", "--input-file"]:
            inputfile = open(sys.argv[ndx + 1], "r")
            continue
        if item in ["-o", "--output-file"]:
            outputfile = open(sys.argv[ndx + 1], "w")
            continue
        if item in ["-f", "--flag"]:
            flag = True
            continue
        if item in ["-h", "--help", "-?"]:
            print(
                sys.argv[0],
                "[--input-file name] [--output-file name] [--flag]",
                file=sys.stderr,
            )
            exit(1)
        raise ValueError(f"unexpected option {item}")

    print("flag", flag)

    outputfile.write(inputfile.read())

---

Implementation of cp using argparse

The contents of cli/20-argpase/__main__.py:

""" copy file implemented with argparse
"""


from argparse import ArgumentParser, FileType

if __name__ == "__main__":

    parser = ArgumentParser()
    parser.add_argument("--input-file", "-i", type=FileType("r"), default="-")
    parser.add_argument("--output-file", "-o", type=FileType("w"), default="-")
    parser.add_argument("--flag", "-f", action="store_true")
    args = parser.parse_args()

    print("flag", args.flag)

    args.output_file.write(args.input_file.read())

---

Implementation of cp using typer

The contents of cli/30-typer/__main__.py:

""" copy file implemented with typer
"""

import typer

cli = typer.Typer()

context_settings = dict(help_option_names=["--help", "-h"])


@cli.command(context_settings=context_settings)
def copy_files(
    input_file: typer.FileText = typer.Option("-"),
    output_file: typer.FileTextWrite = typer.Option("-"),
    flag: bool = False,
) -> None:
    """Copy input file to the named output file."""

    print("flag", flag)
    output_file.write(input_file.read())


if __name__ == "__main__":
    cli()

---

Implementation of cp using click

""" copy file implemented with click
"""

import click


@click.command()
@click.option("input-file", type=click.File("r"))
@click.option("output-file", type=click.File("w"))
def copy_files(input_file, output_file, flag):
    """Copy input file to the named output file."""
	
    print("flag", flag)
    output_file.write(input_file.read())


if __name__ == "__main__":
    copy_files()

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