Learning Perl 6

Chapter 8. Files and Directories, Input and Output

Reading and writing text are the bread and butter of many of the programs you’ll want to write. You’ll store data in files and retrieve that data later. This chapter is all about the features you need to do that. Along the way you’ll see how to deal with file paths, move files around, and work with directories. Most of this is done with the same syntax that you’ve already seen, but now with different types of objects.

Many of the tasks in this chapter can fail for reasons that exist outside of your program. If you expected to work in a different directory or a certain file to exist, you might not want to continue if those conditions aren’t true. That’s just the reality of a program that deals with external resources.

File Paths

An IO::Path object represents a file path. It knows how to put together and take apart paths based on your filesystem’s rules. It doesn’t matter if that path is to a file that actually exists, as long as the form of the path obeys those rules. You’ll see how to deal with missing files in a moment. For now, call .IO on any Str to turn it into an IO::Path object:

my $unix-path = '/home'.IO;
my $windows-path = 'C:/Users'.IO;

To build a deeper path, use .add, which allows you to add more than one level at a time:

my $home-directory = $unix-path.add: 'hamadryas';
my $file = $unix-path.add: 'hamadryas/file.txt';

Assign back to your original object if you want to build the path there:

$unix-path = $unix-path.add: 'hamadryas/file.txt'; ...