Working with Filesystem Paths in Python

• Manipulating paths as plain strings is error-prone and OS-specific.
• pathlib provides an object-oriented, cross-platform way to handle paths.
• Path objects offer intuitive operators and methods for most filesystem tasks.

Limitations of String Paths and os.path

• Using os.path.join, os.path.exists, etc., requires multiple function calls.
• Code readability suffers when paths are manipulated as plain strings.
• OS differences ("/" vs "\" separators) must be handled explicitly.

Creating and Combining Path Objects

• Import Path from pathlib.
• Create Path objects for directories and files.
• Use the / operator to join path components cleanly.

from pathlib import Path

config_dir = Path(".")
filename = "settings.yaml"

print(config_dir, type(config_dir))

config_path = config_dir / filename
print(config_path.resolve())

Inspecting Path Properties

• .exists(), .is_file(), .is_dir() check path state.
• .parent, .name, .stem, .suffix expose components.
• .resolve() returns the absolute, canonical path.

service_log = Path("/var/log/app/service.log")

print(f"Exists: {service_log.exists()}")
print(f"Is file? {service_log.is_file()}")
print(f"Is directory? {service_log.is_dir()}")
print(f"Parent: {service_log.parent}")
print(f"Name: {service_log.name}")
print(f"Stem: {service_log.stem}")
print(f"Suffix: {service_log.suffix}")
print(f"Resolved absolute path: {service_log.resolve()}")

Listing Directory Contents

• .iterdir() yields immediate children of a directory.
• .glob(pattern) finds entries matching a shell-style pattern.
• Use "**/*.ext" in glob for recursive searches.

course_parent = Path("..")

print("Immediate children:")

for i, child in enumerate(course_parent.iterdir()):
    print(f"  {child.name} - {child.is_dir()}")
    if i >= 4: break

print("Python files recursively:")

for i, child in enumerate(course_parent.glob("**/*.ipynb")):
    print(f"  {child}")
    if i >= 10: break

Reading and Writing Files with Path

• .write_text() and .read_text() handle simple text I/O.
• Use p.open(mode="a") for more control (e.g., appending, binary mode).
• Path methods automatically manage file open/close.

test_file = Path("demo.txt")

test_file.write_text("Hello, from pathlib!", encoding="utf-8")
print(f"Read back: {test_file.read_text(encoding="utf-8")}")

with test_file.open(mode="a", encoding="utf-8") as file:
    file.write("\nAppended line!")

print(f"Read back: {test_file.read_text(encoding="utf-8")}")

test_file.unlink()