What reasons are there to prefer glob over readdir (or vice-versa) in Perl?

Question

This question is a spin-off from this one. Some history: when I first learned Perl, I pretty much always used `glob` rather than `opendir` + `readdir` because I found it easier. Then later various posts and readings suggested that `glob` was bad, and so now I pretty much always use `readdir`. After thinking over this recent question I realized that my reasons for one or the other choice may be bunk. So, I'm going to lay out some pros and cons, and I'm hoping that more experienced Perl folks can chime in and clarify. The question in a nutshell is are there compelling reasons to prefer `glob` to `readdir` or `readdir` to `glob` (in some or all cases)? `glob` pros: - No dotfiles (unless you ask for them) - Order of items is guaranteed - No need to prepend the directory name onto items manually - Better name (c'mon - `glob` versus `readdir` is no contest if we're judging by names alone) (From ysth's answer; cf. `glob` cons 4 below) Can return non-existent filenames: ``` @deck = glob "{A,K…

Accepted Answer

You missed the most important, biggest difference between them: `glob` gives you back a list, but `opendir` gives you a directory handle. You can pass that directory handle around to let other objects or subroutines use it. With the directory handle, the subroutine or object doesn't have to know anything about where it came from, who else is using it, and so on:

```
 sub use_any_dir_handle {
      my( $dh ) = @_;
      rewinddir $dh;
      ...do some filtering...
      return \@files;
      }
```

With the dirhandle, you have a controllable iterator where you can move around with `seekdir`, although with `glob` you just get the next item.

As with anything though, the costs and benefits only make sense when applied to a certain context. They do not exist outside of a particular use. You have an excellent list of their differences, but I wouldn't classify those differences without knowing what you were trying to do with them.

Some other things to remember:

You can implement your own glob with `opendir`, but not the other way around.

glob uses its own wildcard syntax, and that's all you get.

glob can return filenames that don't exist:

```
$ perl -le 'print glob "{ab}{cd}"'
```

What reasons are there to prefer glob over readdir (or vice-versa) in Perl?

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