[−][src]Crate econtext
econtext: fast and simple error context on panics.
Calling an econtext!
macro adds a scope to a thread-local linked list. If there is a panic!()
while the scope is active, the data/message provided to the econtext!
macro will be printed.
This thus provides an opt-in stack trace with optional data (e.g. the values of function arguments).
This can be very useful, for instance:
- To print what data was being worked on when an error occurred
- To provide something similar to a stack trace where a real stack trace is not available (e.g. in some WASM contexts)
- To print a shorter and more readable stack trace for when the real stack trace is too long and winding.
The overhead of calling an excontext
macro is around 15ns on a 2020 MacBook Pro.
Example
use econtext::*; fn main() { econtext::add_panic_hook(); // Ensures econtext is printed on panic econtext!("While running"); // Print a message if there is a panic run(); } fn run() { econtext_function!(); // Print function name (`run`) if there is a panic process("filename.txt"); } fn process(filename: &str) { econtext_function_data!(filename.to_owned()); // Print function name and filename if there is a panic for i in 0..10 { econtext_data!("i", i); // Print loop index if there is a panic assert!(i != 4, "Intentional panic"); } }
On error, something like this is printed:
ERROR CONTEXT:
my_module src/main.rs:17: i 4
my_module src/main.rs:15: main::process "filename.txt"
my_module src/main.rs:10: main::run
my_module src/main.rs:5: While running
Macros
current_function_name | |
econtext | Provide a single |
econtext_data | Provide a |
econtext_function | Provide current function name as context. |
econtext_function_data | Provide current function name and some data as context. |
Structs
DataScope | What is put in a stack frame that uses the macros. |
EmptyDebug | Used internally when not having any data in a context scope. |
Constants
ERROR_STACK |
Traits
Entry | The trait for an entry in the stack |
Functions
add_panic_hook | Call this once to add a panic hook that calls |
econtext_string | Returns the error context as a string. |
print_econtext | Prints all active error contexts to stderr. |
type_name_of |