how to check syntax of code inside a scalar?

[tjking]

Hi all, I've got some scripts that dynamically load Perl snippets from the filesystem, setup a few things for them, and then run them through eval(). Is there a way to check the syntax of code contained inside a scalar without having to run 'perl -c' on the external file? TIA

[tilly]

If you want the check to be right, then no. Nothing but perl can parse Perl.

However Perl::Tidy does a usually acceptable job of figuring out Perl syntax.

[tjking]

Uggh, it's a bit shortsighted that there's no built-in function for this. However, after playing a bit, I've found that this can be simulated without having to actually execute the scalar's contents by pre-pending "return;" and testing with eval:

sub syntax_ok {
        my $source = "return;\n" . shift;
        eval $source;
        return 1 unless $@;
        return 0;
}

Thanks!

[Crackers2]

Bad idea... try it with this:

syntax_ok(qq{BEGIN { print "yay\n"; }});

and you'll see that the BEGIN block still gets run, bypassing your return statement. So I'd consider it rather unsafe.