how to call another subroutine after the return statement

Question

How can I call another subroutine from existing subroutine just after the return statement in perl. I dont want to call before the return statement as it is taking time to render. I do not want to wait. return it and then call another subroutine before the exit. Is it possible in perl?

Please explain your problem better. As stated, your request makes no sense. You can't do something before the sub is exited but after it executes a `return`, because the whole point of `return` is to exit the sub. — ikegami, Jun 05 '19 at 10:37
Write a wrapper for the routine from which you want to return without undue wait, in which you call that routine (and so it returns) and then call the other one. — zdim, Jun 05 '19 at 10:44
@zdim Can you please give me an example of what you are suggesting — Dumb, Jun 05 '19 at 10:52
It sounds like what you want is an `after` method modifier. If you use Moose inside of Mojolicious, you have the Moose implementation available. If you don't, you could use Class::Method::Modifiers. If you're talking about Actions in Mojo, I am not sure what willl happen if you combine that. If you can alter the sub you want something to execute after, you can always go `return do{ foo(); $original_return_value }` — simbabque, Jun 05 '19 at 11:55
Thanks @simbabque. But can I do something like return do{$original_return_value; foo() } — Dumb, Jun 05 '19 at 12:13
That would discard the original return value and return the return value of `foo()`. So that doesn't make sense. — simbabque, Jun 05 '19 at 13:38
Like `sub wrapper { original(); slow() };` and add handling of returns etc. — zdim, Jun 05 '19 at 16:05

score 5 · Accepted Answer · answered Jun 05 '19 at 12:35

5

You can fork and run your subroutine in a new process while the original process is returning.

sub do_something {
    my ($var1, $var2, $var3) = @_;
    my $output = ...

    if (fork() == 0) {
        # child process
        do_something_else_that_takes_a_long_time();
        exit;
    }
    # still the parent process
    return $output;
}

answered Jun 05 '19 at 12:35

mob

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Thanks a lot. That serves the need – Dumb Jun 05 '19 at 12:46

score 1 · Answer 2 · answered Jun 05 '19 at 13:42

Your question is tagged as Moose, so here is how you do what you want with a method modifier. The after modifier runs after a sub is, but its return value is ignored.

package Foo;
use Moose;

sub frobnicate {
  my $self = shift;

  # ...

  return 123;
}

after frobnicate => sub {
  my ($self, $rv) = @_;

  $self->barnicate;
};

1;

Now whenever frobnicate is done, barnicate will be called.

how to call another subroutine after the return statement

2 Answers2