Re^2: while following perl hack book

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Re^3: while following perl hack book by ysth (Canon) on Feb 04, 2008 at 08:59 UTC
sub { some code } generates an anonymous subroutine and returns a reference to it. So: `find( { wanted => sub { blah blah } }, @dirs );` [download] is the same as `sub foo { blah blah } find( { wanted => \&foo }, @dirs );` [download] but without declaring a separate, named subroutine. Update: fixed to pass hashref and array -- Online Fortune Cookie Search	[reply] [d/l] [select]
Re^4: while following perl hack book by convenientstore (Pilgrim) on Feb 04, 2008 at 20:04 UTC
I understand now about the anonymous subroutine. I went over both anonymous sub and also the cpan's doc on this at http://search.cpan.org/~rgarcia/perl-5.10.0/lib/File/Find.pm However, I still do not understand .. Doc says that find(\&wanted, @directories);, find function will do a depth search in @directories and for each file/dir found, it will call a anonymous sub wanted couple questions 1)why is there a curly brace for find at below? find{}, instead of bracket?? All the example I been looking at has find() 2)why are they omitting the second parameter ? list of directories? Or shouldn't the whole thing be written as `find( sub { ##code here; }, @INC, );` [download] instead of how it's written in the book? `find{ wanted => sub { ##### code ;}, no_chdir => 1,}, $incl_dir;` [download]	[reply] [d/l] [select]
Re^5: while following perl hack book by ysth (Canon) on Feb 04, 2008 at 20:11 UTC
Look at the synopsis in File::Find again. Passing a hashref instead of a coderef (i.e. `{ wanted => ..., }`) allows (but doesn't require) you to specify other options, like no_chdir or follow. -- Online Fortune Cookie Search	[reply] [d/l]
Re^5: while following perl hack book by Util (Priest) on Feb 05, 2008 at 02:45 UTC
The hack author just omitted the parens. When `find` is predeclared (or imported in this case), these two lines are identical: `find sub { ... }, $dir_name ; find( sub { ... }, $dir_name );` [download] I thought that as well, but when I tried to refactor to the more efficient form (passing all directories at once), I noticed that the code in the &wanted sub needs to know the "root" directory name: `$file =~ s{^\Q$incl_dir/\E}{ };`. Passing all the dirs at once removes the ability to see `$incl_dir`.	[reply] [d/l] [select]
Re^6: while following perl hack book by convenientstore (Pilgrim) on Feb 05, 2008 at 04:58 UTC
Re^3: while following perl hack book by Util (Priest) on Feb 05, 2008 at 02:33 UTC
++ysth is correct about named vs anonymous subroutines. Another confusing issue is that the first argument to find() can be either a code reference or a hash reference. In the simpler case, where you have no special options to set, you just make the first argument a code reference; a reference to the "callback" sub. The sub is always named "wanted" in the documentation, but it can have any name, or be a anonymous sub. `find( \&some_subroutine, @directories_to_search, );` [download] If you need to set a special option in find(), like 'no_chdir', then you pass a hash reference as the first argument. The code reference (that you would have used as the first argument in the simpler case) becomes the 'wanted' option. `find( { wanted => \&some_subroutine, other_option => 'other_option_value', # ... }, @directories_to_search, );` [download]	[reply] [d/l] [select]