File handling klyn.io Paths

File Handling with klyn.io

The klyn.io package provides path abstractions, text readers and writers, byte streams, and file/folder helpers. It is the foundation used by CSV, JSON, XML, archive, and XLSX APIs.

Imports

Only the base klyn package is imported automatically. File code must import klyn.io explicitly.

import klyn.io

Paths

Path represents a filesystem location. Use FilePath when you know the target is a file, and FolderPath when you know it is a directory. The static properties Path.cwd, Path.home, Path.klynHome, and Path.tempDir are convenient anchors for portable code.

import klyn.io

root = Path.cwd
logs = FolderPath(root, "logs")
report = FilePath(logs, "startup.log")

print(root.toString())
print(report.parent())

Prefer Path APIs over string concatenation

Path helpers keep separators, normalization, and platform-specific filesystem rules in one place. Build paths with constructors, resolve, Path.file, or Path.folder instead of manually appending / or \.

Text Files

For concise full-file text operations, Path.read() and Path.write(...) read or replace the complete file content. For explicit resource control, streaming, or line-by-line processing, use FileReader and FileWriter.

import klyn.io

file = Path.tempDir.resolve("klyn-notes.txt")
try:
    file.write("First line\nSecond line")
    print(file.read())
finally:
    if file.exists:
        file.remove()

The next form is more verbose but gives explicit control over resource lifetime. A FileWriter truncates the target when it opens, then FileReader reads the content back. The nested try writer = ...: and try reader = ...: blocks close the resources deterministically.

import klyn.io

file = Path.tempDir.resolve("klyn-notes.txt") as FilePath
try:
    try writer = FileWriter(file):
        writer.write("First line\nSecond line")

    assert file.exists
    assert file.isRegular

    try reader = FileReader(file):
        print(reader.readAllText())
finally:
    if file.exists:
        file.remove()

For line-oriented files, keep the reader and writer APIs. writeLine(...) appends the platform line terminator, and readLines() returns the lines from the current reader position. This is the preferred style for logs, configuration files, and data formats that are naturally processed one line at a time.

import klyn.io

path = Path.tempDir.resolve("klyn-lines.txt")
try:
    try writer = FileWriter(path):
        writer.writeLine("alpha")
        writer.writeLine("beta")

    try reader = FileReader(path):
        for line in reader.readLines():
            print(line)
finally:
    if path.exists:
        path.remove()

Folders

FolderPath can create one directory with mkdir(), create a whole tree with mkdirs(), list children, and remove a tree with removeAll().

import klyn.io

tmp = FolderPath(Path.tempDir, "klyn-export", "nested")
try:
    tmp.mkdirs()
    try writer = FileWriter(FilePath(tmp, "data.txt")):
        writer.write("payload")

    for name in tmp.listNames():
        print(name)
finally:
    if tmp.exists:
        tmp.removeAll()

Resource Safety

Path.read() and Path.write(...) are convenient full-file helpers. Readers, writers, and streams should still be opened with try resource = ...: when you need incremental I/O, so the runtime closes them even if an exception is raised. FileReader, FileWriter, FileInputStream, and FileOutputStream provide that explicit control.