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Perl 6 Deep Dive

You're reading from   Perl 6 Deep Dive Data manipulation, concurrency, functional programming, and more

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Product type Paperback
Published in Sep 2017
Publisher Packt
ISBN-13 9781787282049
Length 402 pages
Edition 1st Edition
Languages
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Author (1):
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Andrew Shitov Andrew Shitov
Author Profile Icon Andrew Shitov
Andrew Shitov
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Toc

Table of Contents (15) Chapters Close

1. What is Perl 6? FREE CHAPTER 2. Writing Code 3. Working with Variables and Built-in Data Types 4. Working with Operators 5. Control Flow 6. Subroutines 7. Modules 8. Object-Oriented Programming 9. Input and Output 10. Working with Exceptions 11. Regexes 12. Grammars 13. Concurrent Programming 14. Functional Programming 15. Reactive Programming

Soft failures

In the previous example, the try block contained the instructions for both math calculations and printing the result. In real programs, these actions are often separated. Let us re-write the program so that it divides the numbers in a separate subroutine:

my $a = prompt 'Enter dividend > ';
my $b = prompt 'Enter divisor > ';
my $c = calculate($a, $b);
say 'Now ready to print';
say "The result of $a / $b is $c.";
say 'Done.';

sub calculate($a, $b) {
    return $a / $b;
}

Now the dangerous action happens inside the calculate function and the result is used outside it.

Run the program with values that should cause exception:

$ perl6 division.pl
Enter dividend > 10
Enter divisor > 0
Now ready to print
Attempt to divide 10 by zero using div
  in block <unit> at 06.pl line 7

Actually thrown at:
  in...
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