Block passing is a concept in Perl that allows you to pass a block of code as an argument to a subroutine. This block of code is then executed in the context of the subroutine. This technique is commonly used in cases where you need to pass complex or variable logic to a subroutine.
Here's an example that demonstrates how to use block passing in Perl:
sub do_something {
my $code_block = shift; # Get the block of code
$code_block->(); # Execute the code block
}
# Define the code block as a subroutine reference
my $code = sub {
my $value = shift;
print "The value is $value\n";
};
# Pass the code block to the do_something subroutine
do_something($code->("hello"));
In this example, we define a subroutine called do_something that takes a code block as an argument. We retrieve the code block from the argument list and execute it by using the ->() syntax.
We then define a code block as a subroutine reference and pass it to the do_something subroutine. The code block takes a single argument and prints it to the screen.
When we call the do_something subroutine, we pass the code block as an argument and call it with a value of "hello". This results in the value being printed to the screen.
This is just a simple example, but block passing can be used in many ways to make your code more modular and reusable.