A peave of mine is when I see people who write Perl scripts and all the work in them is done by using system() calls. What is the point in writing a Perl script if you're not going to use the Perl functions? You might as well write the thing in shell.

And a "peave" of me is people who see everything black-and-white. I've written Perl programs where the majority of the work was done doing "system". What's the point of using a glue language, and not glueing? You might as well write the thing in C.

Your point of view is quite opposite of the viewpoint of "code reuse". Unix comes with a handy toolkit. There's nothing wrong with using it.

You might as well write the thing in shell.

Not always. Perl gives you more control flow syntax than a shell.

Spawning system calls does take more resources and thus it behooves the Perl programmer to try and code the functionality they want using Perl built-ins and modules.

Bull. Programming means making trade-offs between developer time and run-time. The fact that you have choosen Perl instead of say, C, means that you strongly favour developer time over run time. Your arguments make sense if you are a C coder - but for a Perl coder they are just silly.

Really, what's the point of writing:

    my $text = do {
        open my $fh => $file or die "open: $!\n";
        local $/;
        <$fh>;
    };
[download]

If you can just write:

    my $text = `cat $file`;
[download]

Most programs won't read in gazillions of files in a single program, so the extra overhead is minute. Far less than the sacrifice you already made by using Perl instead of C. I also prefer

    system mkdir => -p => $dir;
[download]

over the Perl equivalent. It takes to long to figure out which module implemented it, and to download and install it.

Of course, making use of external programs makes you less portable, but so does making use of modules not coming with the core. And many programs dealing with file names aren't portable anyway. Do you always use File::Spec when dealing with file names? I certainly don't.

I'm not claiming everything should be done with system. Not at all. But I don't thing that everything that can be done in Perl should, and that therefore system should be avoided.

Abigail

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