Add feature to pass additional arguments on to coderef

[dboehmer]

Thank you for this great module. I've written minimal versions of this multiple times and have just found this concise solution on CPAN! 👍

Would you mind adding a feature that you can provide additional arguments that get passed on to the provided coderef?

my $guard = guard { do_something_with_foo(@_) }, $foo, $bar, ...;

The difference to

my $guard = guard { do_something_with_foo($foo, $bar, ...) };

is obviously the execution time of $foo etc. I have a long living LWP::UserAgent object and need to temporarily set its max_redirect to 0. I'd love to write this:

my $ua = LWP::Simple->new();
...
subtest "test some redirect" => sub {
    my $guard = guard { $ua->max_redirect(@_) }, $ua->max_redirect; # will restore original value 
    $ua->max_redirect(0); # temporarily
    ...
};
...

As far as I studied your code no existing code could be using any additional arguments and they could easily stored in @$self.

I'd send a PR if you consider adding this feature.

[karenetheridge]

Not the author, but I think you can achieve that with the use of the curry module (https://metacpan.org/pod/curry).

[dboehmer]

I've never used curry before but just had I a look at it. I don't get how this would help here, though.

The documentation of curry is all about weak references. Instead my problem is

1. I want to run code automatically once the current scope block ends: Scope::Guard solves this by establishing a variable that calls my code once its garbage-collected.
2. For that I need to save some information (the original value of max_redirect) for the meantime.

This issue is only about how to conveniently save that information in (2). Without that I need to write

my $original_max_redirect = $ua->max_redirect;
my $guard = guard { $ua->max_redirect($original_max_redirect) } # will restore original value 
$ua->max_redirect(0); # temporarily
...

This could be shortened by passing the original value along. How could curry help here? If I am just not getting it, please be as kind as posting an example code.

[karenetheridge]

The documentation of curry is all about weak references.

Not at all; it's about wrapping up extra arguments in a closure for re-use. You can write the closure yourself, but curry does it with shorter code.

This is fairly simple; does this do what you're looking for?

{ # begin new scope
    my $original_max_redirect = $ua->max_redirect;
    my $guard = guard { $ua->max_redirect($original_max_redirect) };
    $ua->max_redirect(0);
    ... test code here...
}

[dboehmer]

Yeah, this is the obvious plain version. I thought I could save that extra line and it might be a neat feature of Scope::Guard anyway as @_ is completely unused at the moment.

Sorry, but how would the shorter code look like using curry?

[karenetheridge]

instead of

    my $original_max_redirect = $ua->max_redirect;
    my $guard = guard { $ua->max_redirect($original_max_redirect) };

you could do:

    use curry;
    my $guard = guard $ua->curry::max_redirect($ua->max_redirect);