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misc/perl6advent-2010/articles/file-operations.pod

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+=head1 File operations
+
+=head2 Directories
+
+Instead of C<opendir> and friends, in Perl 6 there is a single C<dir>
+subroutine, returning a list of the files in a specified directory,
+defaulting to the current dirrectory. A piece of code speaks a thousand
+words:
+
+    # in the Rakudo source directory
+    > dir
+    build parrot_install Makefile VERSION parrot docs Configure.pl README dynext t src tools CREDITS LICENSE Test.pm
+    > dir 't'
+    00-parrot 02-embed spec harness 01-sanity pmc spectest.data
+
+C<dir> has also an optional named parameter C<test>, used to grep the
+results
+
+    > dir 'src/core', test => any(/^C/, /^P/)
+    Parcel.pm Cool.pm Parameter.pm Code.pm Complex.pm CallFrame.pm Positional.pm Capture.pm Pair.pm Cool-num.pm Callable.pm Cool-str.pm
+
+Directories are created with C<mkdir>, as in C<mkdir('foo')>
+
+=head2 Files
+
+The easiest way to read a file in Perl 6 is using C<slurp>. C<slurp> returns the contents of a file, as a String,
+
+    > slurp 'VERSION'
+    2010.11
+
+The good, old way of using filehandles is of course still available
+
+    > my $fh = open 'CREDITS'
+    IO()<0x1105a068>
+    > $fh.getc # reads a single character
+    =
+    > $fh.get # reads a single line
+    pod
+    > $fh.close; $fh = open 'new', :w # open for writing
+    IO()<0x10f3e704>
+    > $fh.print('foo')
+    Bool::True
+    > $fh.say('bar')
+    Bool::True
+    > $fh.close; say slurp('new')
+    foobar
+
+=head2 File tests
+
+Testing the existence and types of files is done with smartmatching (~~).
+Again, the code:
+
+    > 'LICENSE'.IO ~~ :e # does the file exist?
+    Bool::True
+    > 'LICENSE'.IO ~~ :d # is it a directory?
+    Bool::False
+    > 'LICENSE'.IO ~~ :f # a file then?
+    Bool::True
+
+Easy peasy.
+
+=head2 File::Find
+
+When the standard features are not enough, modules come in handy.
+C<File::Find> (available in the C<File::Tools> package) traverses the
+directory tree looking for the files you need, and generates a lazy
+lists of the found ones. File::Find comes shipped with Rakudo Star,
+and can be easily installed with C<neutro> if you have just a
+bare Rakudo.
+
+Example usage? Sure. C<<find(:dir<t/dir1>, :type<file>, :name(/foo/))>>
+will generate a lazy list of files (and files only) in a directory named
+t/dir1 and with a name matching the regex C</foo/>. Notice how the
+elements of a list are not just plain strings: they're objects which
+strinigify to the full path, but also provide accessors for the directory
+they're in (C<dir>) and the filename itself (C<name>). For more info
+please refer to the C<documentation>.
+
+=head2 Useful idioms
+
+=over 4
+
+=item Creating a new file
+
+    open('new', :w).close
+
+=item "Anonymous" filehandle
+
+    given open('foo', :w) {
+        .say('Hello, world!');
+        .close
+    }
+
+=back