Protect from undef values in Mojo::File objects

[kraih]

It is currently very easy to delete the wrong directory by accident, like:

my $subdir = undef;
path('usr', 'share', $subdir)->remove_tree;

This would currently delete usr/share and only show a pretty insignificant warning about the undef value. I noticed the problem because we had a similar accident at work. 😉

$ perl -Mojo -E 'n { f("foo", "bar", "baz")->child("yada") } 1000000'
2.67053 wallclock secs ( 2.67 usr +  0.00 sys =  2.67 CPU) @ 374531.84/s (n=1000000)

$ perl -Ilib -Mojo -E 'n { f("foo", "bar", "baz")->child("yada") } 1000000'
2.80627 wallclock secs ( 2.81 usr +  0.00 sys =  2.81 CPU) @ 355871.89/s (n=1000000)

The performance cost is pretty minimal. I would have liked to include the empty string too, but unfortunately we depend on that currently for a Mojo::Home hack that i don't dare to change again.

[kraih]

I'm not 100% sure if it is worth the performance cost, but i'm giving it a 👍 personally and call for a vote anyway @mojolicious/core.

[christopherraa]

If I had voting rights I'd be 👍 for this. I've fallen into this trap myself.

[marcusramberg]

Im 👍

_{Sent with GitHawk}

[jberger]

👍

[jberger]

I've already voted in favor but can you explain the significance of this line?

[kraih]

Totally insignificant. It's an optimization that's already in master actually. 😆

[kraih]

It makes ->child calls a lot faster though since it avoids stringification later.