Re^2: Importing Time::HiRes::time at run-time (and failing)

Aha! Thanks for the cogent explanation. Along with some advice from bart on the chatterbox, I came up with the following proof-of-concept solution.

#! /usr/local/bin/perl -l

package P;

sub new {
    my $class = shift;
    my $mod   = shift;
    eval "use $mod ()";
    my $self = {};
    if ($@) {
        $self->{_time_func} = sub { time };
    }
    else {
        $self->{_time_func} = sub { Time::HiRes::time() };
    }
    return bless $self, 'P'
}

package main;

my $p = P->new( shift || 'Time::HiRes' );

print $p->{_time_func}->();
sleep 2;
print $p->{_time_func}->();
[download]

You can run this, and if T::HR is installed, you get fractional times. Pass it junk on the command line, and then T::HR is not loaded (which simulates what happens on an installation that lacks it, or fails to load) and integer seconds come out.

In the real world, the _time_func business will be hidden from the user, they just get back fractional seconds, or not.

• another intruder with the mooring in the heart of the Perl

Comment on Re^2: Importing Time::HiRes::time at run-time (and failing) Download Code

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Re^3: Importing Time::HiRes::time at run-time (and failing) by salva (Canon) on Apr 20, 2006 at 15:28 UTC
you can simplify it a bit replacing the `eval "..."` by a `eval {...}` and returning a reference to `Time::HiRes::time` instead of it wrapped inside an additional sub: `package P; sub new { my $class = shift; my $self = {}; $self->{_time_func} = eval { require Time::HiRes } ? \&Time::HiRes::time : sub { time() }; bless $self, $class }` [download]	[reply] [d/l] [select]