Summary
When no file paths are provided and stdin is a terminal (not a pipe), repren silently enters stdin mode and blocks waiting for input. This is confusing when a user simply forgets to provide file arguments.
Details
In repren.py (around line 1603), stdin mode is activated when len(options.root_paths) == 0. There is no check for whether stdin is actually a pipe or a terminal.
Compare with common Unix tools like cat which also read from stdin by default — but unlike cat, repren's purpose is primarily file processing, so accidentally entering stdin mode is more likely to be a mistake.
Suggestion
When stdin is a terminal (not piped), print a helpful message to stderr before reading, e.g.:
repren: reading from stdin (use Ctrl-D to end input, or provide file paths)
Or, more aggressively, refuse to read from a terminal and print a usage hint:
repren: error: no paths provided and stdin is a terminal
Run `repren --help` for usage.
The Rust port (repren-rs) uses std::io::IsTerminal to detect this case and prints a hint.
Summary
When no file paths are provided and stdin is a terminal (not a pipe), repren silently enters stdin mode and blocks waiting for input. This is confusing when a user simply forgets to provide file arguments.
Details
In
repren.py(around line 1603), stdin mode is activated whenlen(options.root_paths) == 0. There is no check for whether stdin is actually a pipe or a terminal.Compare with common Unix tools like
catwhich also read from stdin by default — but unlikecat, repren's purpose is primarily file processing, so accidentally entering stdin mode is more likely to be a mistake.Suggestion
When stdin is a terminal (not piped), print a helpful message to stderr before reading, e.g.:
Or, more aggressively, refuse to read from a terminal and print a usage hint:
The Rust port (
repren-rs) usesstd::io::IsTerminalto detect this case and prints a hint.