Catch and throw is similar raise and rescue keywords exceptions can also be handled using catch and throw keywords in ruby.
Ruby catch exception and continue.
When ruby encounters a throw it zips back up the call stack looking for a catch block with a matching symbol.
This article will discuss the use of exceptions and show some examples of how to deal with them.
Throw keyword generates an exception and whenever it is met the program control goes to the catch statement.
Catch defines a block that is labeled with the given name which may be a symbol or a string.
A beginner s guide to exceptions in ruby.
The begin is omitted and the entire body of the method is subject to exception handling ending.
Ruby s standard classes and modules raise exceptions.
The exception mechanism in ruby is very powerful but often misused.
When it finds it ruby unwinds the stack to that point and terminates the block.
Rescue clause is used to handle the exceptions created by raise.
By starr horne author.
Returns the previous exception at the time this exception was raised.
All the exception classes form a hierarchy with the class exception at the top.
The block is executed normally until a throw is encountered.
The catch defines a block that is labeled with the given name which may be a symbol or a string.
Static value exc cause value exc return rb attr get exc id cause.
This is useful for wrapping exceptions and retaining the original exception information.
The ruby standard library defines about 30 different subclasses of exceptions some of which have their own subclasses.
Ruby uses the kernel method termed as raise to create the exceptions which will be the instance of exception class or one of its subclass.
It is to be noted that the body of a method definition is an implicit begin end block.
To do exception handling we enclose the code that could raise an exception in a begin end block and use one or more rescue clauses to tell ruby the types of exceptions we want to handle.
In a nutshell every custom ruby exception should extend standarderror rather than the exception class the reason for this is outlined in exception handling in ruby with this in mind the simplest custom exception class that we can define will look something like this.
Catch lable name do matching catch will be executed when the throw block encounter throw lable name.
I hope you find it useful.
