Homework: wc Clone

作业: wc 克隆

≈ 45 min · python-cmdline python-file-io python-functions · Open in WolfCode

A clone of Unix wc. Five functions: three counters, one orchestrator, one parser.

The five functions

count_lines(path) — int
count_words(path) — int
count_chars(path) — int (includes newlines)
count_all(path) — tuple, calls the three above
parse_args(argv) — argparse with path + 3 flags

The shape

Python · runnable

import argparse
import sys

def count_lines(path):
    with open(path) as f:
        return sum(1 for _ in f)

def count_words(path):
    with open(path) as f:
        return sum(len(line.split()) for line in f)

def count_chars(path):
    with open(path) as f:
        return sum(len(line) for line in f)

def count_all(path):
    return (count_lines(path), count_words(path), count_chars(path))    # composition

def parse_args(argv):
    parser = argparse.ArgumentParser(description="Count lines, words, characters.")
    parser.add_argument("path", help="Path to the file to count")
    parser.add_argument("--lines", action="store_true")
    parser.add_argument("--words", action="store_true")
    parser.add_argument("--chars", action="store_true")
    return parser.parse_args(argv)

# In Pyodide, demonstrate with an in-memory file:
with open("demo.txt", "w") as f:
    f.write("the quick brown fox\njumps over the lazy dog\n")

print(count_all("demo.txt"))     # (2, 9, 45)

Loading Python runtime (~5 MB, one-time)…

Acceptance criteria

All 8 tests pass
Each counter uses with open(...)
count_all calls at least 2 of the 3 counters
parse_args accepts path + --lines / --words / --chars