Reading stdin input

Read from stdin by installing a handler with env.stdin_install. The handler receives data as it arrives. In the common text case, the data is decoded to str.

actor main(env):
    def interact(input):
        print("Got some input:", input)

    env.stdin_install(interact)

You can make the text decoding explicit by providing on_stdin, encoding, and on_error.

When encoding is not set, Acton tries to discover the encoding from LANG. If nothing useful is found, it falls back to UTF-8.

actor main(env):
    def interact(input):
        print("Got some input:", input)

    def on_stdin_error(err, data):
        print("Some error with decoding the input data:", err)
        print("Raw bytes data:", data)

    env.stdin_install(on_stdin=interact, encoding="utf-8",
        on_error=on_stdin_error)

If the data is binary, or if you want to delay decoding, install a bytes handler instead.

actor main(env):
    def interact(bytes_input):
        # Decode only when this code is ready to decide how.
        print("Got some input:", bytes_input.decode())

    env.stdin_install(on_stdin_bytes=interact)

The important distinction is between a decoded text stream and a raw byte stream. If the input protocol is truly textual, the string path is usually right. If framing, binary payloads, or uncertain encodings matter, keep the data as bytes until your own code decides how to decode it.

Common patterns

Use the text callback for ordinary command line input, especially when the input is line-oriented or clearly textual.

Use the bytes callback when the input may contain binary data, partial fragments of multibyte characters, or a protocol with its own framing rules.

Treat decode errors as part of the interface. If the program expects text, decide what to do when the bytes do not decode cleanly instead of letting that decision hide inside a helper.

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Acton Guide

Reading stdin input

Common patterns