- Feature Name:
- Start Date: 2015-03-25
- RFC PR: rust-lang/rfcs#1014
- Rust Issue: rust-lang/rust#25977
println! it currently causes a panic if
stdout does not exist. Change this to ignore this specific error and simply void the output.
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 attempting to print to the console.
When using any of the convenience macros that write to either
stderr, such as
assert!, change the implementation to ignore the specific error of
stderr not existing. The behavior of all other errors will be unaffected. This can be implemented by redirecting
std::io::sink if the original handles do not exist.
Update the methods
std::io::stderr as follows:
stderrdoes not exist, return the equivalent of
stdindoes not exist, return the equivalent of
- For the raw versions, return a
Result, and if the respective handle does not exist, return an
- Hides an error from the user which we may want to expose and may lead to people missing panicks occurring in threads.
- Some languages, such as Ruby and Python, do throw an exception when stdout is missing.
assert!return errors that the user has to handle. This would lose a large part of the convenience of these macros.
- Continue with the status quo and panic if
std::io::stderr, make them return a
Result. This would be a breaking change to the signature, so if this is desired it should be done immediately before 1.0. ** Alternatively, make the objects returned by these methods error upon attempting to write to/read from them if their respective handle doesn't exist.
- Which is better? Breaking the signatures of those three methods in
std::io, making them silently redirect to
sink, or erroring upon attempting to write to/read from the handle?