I happen to like modifiers, such as "do this unless that", or "perform this code foreach of these". But I like them usually when I want the action to seem (to the reader of the code) like the most important part of that statement, and in fact, the default behavior. There are, of course, exceptions to that rule. For example, I see nothing wrong with "next unless $line; inside a file-reading loop where I've just chomped and want to move on to the next line if this one turned out to be blank. But for the most part, I prefer my modifiers to be all about actions that I want to have happen except for some less common circumstance.

Keeping that in mind, I would change your die "Usage..." unless @ARGV == 2; to a slightly different idiom. 

@ARGV == 2 or die "Usage.....";

[download]

Now you've got the condition of death right up front so that a reader will see what's triggering the death; too many elements in @ARGV. This is the same approach commonly used with file open. You will find a strong recommendation in that direction for mostly the same reasons I've given in perlstyle. But to be fair, this is a gray area, and you do see it both ways all the time.

I also don't like the notion of setting up aliases to $File::Find::name using typeglobs. These variables are read-only according to the POD for File::Find. When you start aliasing them, you might not remember that $name is special, and shouldn't be modified.

I would much rather just see you checking $File::Find::name directly, or assigning its value to a lexical $name.

The next thing that bothers me is in your $wanted->() sub. You're not checking for the validity of your pattern match, and then you're subsequently relying on $2 to contain a reasonable value. Don't rely on captures unless you're certain that there was a match. Just don't; you will get into trouble eventually with that approach.


Dave

In reply to Re: Copy Permissions by davido
in thread Copy Permissions by BuddhaNature

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