Crate here[−][src]

Expand description

One of the oldest and still most commonly used debugging techniques looks something like this:

// Do something
println!("here");
// Do something else

Or if you’re feeling real fancy:

// Do something
println!("here 1");
// Do something else
println!("here 2");
// Do yet another thing

It’s rather crude, but it’s effective… as long as you can find where you put the print statements.

Well, here is here to help! Usage is simple:

here!(); // prints "filename:lineno" to stdout

What’s that? You want to print to stderr instead of stdout? Then just use ehere. It’s the same great taste as here, but with stderr!

Oh? So you’ve decided to use the wonderful log crate? Don’t worry, we’ve got you covered there, too. With the optional log feature enabled, you get five new macros! One for each log level!

here_trace!(); // log a trace message of "filename:lineno"
here_debug!(); // log a debug message of "filename:lineno"
here_info!(); // log a info message of "filename:lineno"
here_warn!(); // log a warn message of "filename:lineno"
here_error!(); // log a error message of "filename:lineno"

Huh? You want add more information? Don’t worry we’ve got you covered. Each here macro can accept a format string and arguments just like the format! macro!

here!("A message."); // prints "(filename:lineno): A message."
here!("Something: 0x{:02x}", 16);  // prints "(filename:lineno): Something: 0x0f"

Feature Flags

log: Adds several macros to work with the log crate.
off_on_release: Makes it so that nothing is printed on release builds (enabled by default).
std: Adds std support (enabled by default). Because println! and eprintln! are both part of the std library, this will get rid of the here and ehere macros. Useful if you’re just using the log crate.

Macros

eherestd

Prints the line number and filename to stderr. Additionally, it can accept a string literal and format arguments like the format! macro.

herestd

Prints the line number and filename to stdout. Additionally, it can accept a string literal and format arguments like the format! macro.

here_debuglog