Print

Print, deprecated: Writer gives print and print_line to every stream.

Source: runtime/io/print.pep

Print

[Deprecated("use 'Writer' instead", "Writer")] trait Print

Deprecated: use Writer instead.

A byte stream that values can be printed to, as the global print prints to standard output.

A type has the trait by providing write_all(data: u8[]); it then gets print and print_line, which write the text to_string makes of a value (the text $"{value}" would hold).

Example

import io;

main(): int {
    var path = io.Directory.temp().join("report.txt");
    var file = io.File.create(path).value();
    file.print("total: ");
    file.print_line(42);
    file.close();
    assert(io.File.read_to_string(path).value() == "total: 42\n", "printed");
    io.File.remove(path);
    return 0;
}

Methods

write_all

write_all(data: u8[]): IoResult<void>

Writes all of data.

Parameters

• data — the bytes to write

Returns

• an Ok result once every byte is written; an error when the stream fails

print

print<T>(value: T): IoResult<void>

Writes the text of value, with no line break after it: a String as it is, anything else through to_string.

Type parameters

• T — the type of value

Parameters

• value — the value to print

Returns

• an Ok result once the text is written; an error as for write_all

Example

file.print("n = ");
file.print(3);   # the file now holds "n = 3"

print_line

print_line<T>(value: T): IoResult<void>

Writes the text of value and a line break (\n), as the global print does on standard output.

Type parameters

• T — the type of value

Parameters

• value — the value to print

Returns

• an Ok result once the line is written; an error as for write_all

Example

file.print_line($"total: {total}");
file.print_line((1, "two"));   # (1, two)