Module jlrs::catch

Try-catch blocks.

Many functions in Julia can throw exceptions, jlrs provides checked and unchecked variants of such functions. The checked variant calls the function in a try-catch block and returns a Result to indicate whether or not the operation succeeded, while the unchecked variant simply calls the function. If an exception is thrown and it isn’t caught the application is aborted. The main disadvantage of the checked variants is that a new try-catch block is created every time the function is called and creating such a block is relatively expensive.

Instead of using the checked variants you can create a try-catch block from Rust with catch_exceptions. This function takes two closures, think of them as the content of the try and catch blocks respectively.

Because exceptions work by jumping to the nearest enclosing catch block, you must guarantee that there are no pending drops when an exception is thrown. See this blog post for more information.

Only local scopes may be created in the try-block, Julia’s unwinding mechanism ensures that any scope we jump out of is removed from the GC stack. Dynamic scopes (i.e. scopes that provide a GcFrame) depend on Drop so jumping out of them is not sound.

Functions

• catch_exceptions^⚠
  Call func, if an exception is thrown it is caught and exception_handler is called. The exception is guaranteed to be rooted inside the exception handler.