diff --git a/0000-template.md b/0000-template.md index d1dad5534c6..3581b5e1735 100644 --- a/0000-template.md +++ b/0000-template.md @@ -1,29 +1,30 @@ -- Start Date: (fill me in with today's date, YYYY-MM-DD) +- Start Date: 2015-03-25 - RFC PR: (leave this empty) - Rust Issue: (leave this empty) # Summary -One para explanation of the feature. +When calling `println!` it currently causes a panic if `stdout` does not exist. Change this to ignore this specific error and simply void the output. # Motivation -Why are we doing this? What use cases does it support? What is the expected outcome? +On linux `stdout` almost always exists, so when people write games and turn off the terminal there is still an `stdout` that they write to. Then when getting the code to run on Windows, when the console is disabled, suddenly `stdout` doesn't exist and `println!` panicks. This behavior difference is frustrating to developers trying to move to Windows. + +There is also precedent with C and C++. On both Linux and Windows, if `stdout` is closed or doesn't exist, neither platform will error when printing to the console. # Detailed design -This is the bulk of the RFC. Explain the design in enough detail for somebody familiar -with the language to understand, and for somebody familiar with the compiler to implement. -This should get into specifics and corner-cases, and include examples of how the feature is used. +Change the internal implementation of `println!` `print!` `panic!` and `assert!` to not `panic!` when `stdout` or `stderr` doesn't exist. When getting `stdout` or `stderr` through the `std::io` methods, those versions should continue to return an error if `stdout` or `stderr` doesn't exist. # Drawbacks -Why should we *not* do this? +Hides an error from the user which we may want to expose and may lead to people missing panicks occuring in threads. # Alternatives -What other designs have been considered? What is the impact of not doing this? +* Make `println!` `print!` `panic!` `assert!` return errors that the user has to handle. +* Continue with the status quo and panic if `stdout` or `stderr` doesn't exist. # Unresolved questions -What parts of the design are still TBD? +* Should `std::io::stdout` return `Err` or `None` when there is no `stdout` instead of unconditionally returning `Stdout`?