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⬅ Back to Table of Contents ⬅ Back to Functional

File I/O

This page documents all user-facing file I/O helpers in Pythonic, including the File class, open modes, quick helpers, and idiomatic usage, with concise examples.

File Modes

Mode String Enum Value Description
"r" FileMode::READ Read only
"w" FileMode::WRITE Write only (truncate)
"a" FileMode::APPEND Append only
"r+" FileMode::READ_WRITE Read and write
"w+" FileMode::WRITE_READ Write and read (truncate)
"a+" FileMode::APPEND_READ Append and read
"rb" FileMode::READ_BINARY Read binary
"wb" FileMode::WRITE_BINARY Write binary (truncate)
"ab" FileMode::APPEND_BINARY Append binary

File Class

Method / Property Description Example
File(filename, mode) Open file with mode (default "r") File("data.txt", "w")
open(filename, mode) Global open function (like Python) open("data.txt", "r")
read() Read entire file as string f.read()
read(n) Read n characters f.read(10)
readline() Read one line f.readline()
readlines() Read all lines as list f.readlines()
write(content) Write string to file f.write("hello")
writeln(content) Write string with newline f.writeln("line")
writelines(lines) Write list of lines f.writelines(list("a","b"))
flush() Flush buffer f.flush()
seek(pos) Seek to position f.seek(0)
tell() Get current position f.tell()
eof() Check if at end of file f.eof()
name() Get filename f.name()
mode() Get mode as string f.mode()
is_open() Check if file is open f.is_open()
close() Close the file f.close()
operator bool() True if file is open if (f) { ... }
begin()/end() Iterator for reading lines for (auto line : f) { ... }

Quick File Helpers

Function Description Example
read_file(filename) Read entire file as string read_file("data.txt")
read_lines(filename) Read all lines as list read_lines("data.txt")
write_file(filename, content) Write string to file write_file("data.txt", "hi")
append_file(filename, content) Append string to file append_file("data.txt", "hi")
write_lines(filename, lines) Write list of lines write_lines("data.txt", list("a","b"))
file_exists(filename) Check if file exists file_exists("data.txt")

Idiomatic Usage

Basic File Reading

using namespace pythonic::file;
File f("data.txt", "r");
var content = f.read();
f.close();

With Statement (RAII)

using namespace pythonic::file;
with_open("data.txt", "r", f) {
    var content = f.read();
}

Quick Helpers

using namespace pythonic::file;
var content = read_file("data.txt");
var lines = read_lines("data.txt");
write_file("out.txt", "hello");
append_file("out.txt", "world\n");
write_lines("out.txt", list("a","b"));

Iterating Over Lines

using namespace pythonic::file;
File f("data.txt");
for (auto line : f) {
    print(line);
}

Notes

  • The File class automatically closes files on destruction (RAII).
  • Use with_open for Python-like with statement semantics.
  • All helpers accept std::string, const char*, or var for filenames.
  • File modes match Python's open() for easy migration.
  • File errors throw PythonicFileError exceptions on failure.

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