capture output from print command to variable in perl

[championsleeper]

i know its possible to get the epoch time in perl using the command
print time;
how can i capture this in a variable in a perl script? i've got a
feeling i'm missing something fundamental from my perl knowledge but
can't find out how to do it in the books i've been through.

 

[Gunnar Hjalmarsson]

i know its possible to get the epoch time in perl using the command
print time;

That statement uses two functions: print() and time(). time() *returns*
the epoch time which is printed to STDOUT by print().

perldoc -f time
perldoc -f print

how can i capture this in a variable in a perl script?

my $time = time;

 

[Chris Mattern]

i know its possible to get the epoch time in perl using the command
print time;

"time" gets the epoch time. "print" just prints it.

how can i capture this in a variable in a perl script? i've got a
feeling i'm missing something fundamental from my perl knowledge but
can't find out how to do it in the books i've been through.

time is a perl built-in function. Here you are then using the built-in
function print to print the value it returns. You can also just assign
that value to a variable:

my $nowtime = time;

perldoc -f time for more information on time. You should probably
read perldoc -f print as well; you seem shaky on what print
actually does.

--
Christopher Mattern

"Which one you figure tracked us?"
"The ugly one, sir."
"...Could you be more specific?"

 

[Tad McClellan]

i know its possible to get the epoch time in perl using the command
print time;
how can i capture this in a variable in a perl script? i've got a
feeling i'm missing something fundamental from my perl knowledge but
can't find out how to do it in the books i've been through.

See the "Assignment Operators" section in:

perldoc perlop

 

[Tintin]

i know its possible to get the epoch time in perl using the command
print time;
how can i capture this in a variable in a perl script? i've got a
feeling i'm missing something fundamental from my perl knowledge but
can't find out how to do it in the books i've been through.

In all your Perl scripting experience, have you never done something like:

$var = 'value';

or

$var = 99;

or

$var = time;

Amazing.

 

[nobull]

i know its possible to get the epoch time in perl using the command
print time;
how can i capture this in a variable in a perl script? i've got a
feeling i'm missing something fundamental from my perl knowledge but
can't find out how to do it in the books i've been through.

As others have pointed out you can simply put the return value of
time() into a variable. But if you really had had a reason to want to
capture the output of print to a variable.

sub subroutine_i_cannot_alter {
print time;
}

my $capture;
{
require AtExit;
open my $capture_handle, '>', \$capture or die $!;
my $saved_handle = select $capture_handle;
my $restore_output_handle = AtExit->new(sub{ select $saved_handle
});
subroutine_i_cannot_alter();
}

print "Captured <<<$capture>>>\n";

 

[Anno Siegel]

As others have pointed out you can simply put the return value of
time() into a variable. But if you really had had a reason to want to
capture the output of print to a variable.

sub subroutine_i_cannot_alter {
print time;
}

my $capture;
{
require AtExit;
open my $capture_handle, '>', \$capture or die $!;
my $saved_handle = select $capture_handle;
my $restore_output_handle = AtExit->new(sub{ select $saved_handle
});
subroutine_i_cannot_alter();
}

print "Captured <<<$capture>>>\n";

AtExit appears to be an interesting module, thanks for mentioning it.

However, I don't see the advantage in using it here. It only hides
the re-selection of the original output handle. This seems to do
the same thing without the obfuscation:

my $capture;
{
open my $capture_handle, '>', \$capture or die $!;
my $saved_handle = select $capture_handle;
subroutine_i_cannot_alter();
select $saved_handle;
}

Anno

 

[strepxe]

thanks all - appreciate the very helpful answers for a newbie .....

 

[nobull]

AtExit appears to be an interesting module, thanks for mentioning it.

Actually the generic AtExit is not a standard module but the less
general purpose module, SelectSaver, is both more applicable here and
now standard.

However, I don't see the advantage in using it here. It only hides
the re-selection of the original output handle.

It also ensures that the handle is restored even if
subroutine_i_cannot_alter() does not return but throws an exception.
It's a bit like using local().

{
require SelectSaver;
open my $capture_handle, '>', \$capture or die $!;
my $restore_output_handle = SelectSaver->new($capture_handle);
subroutine_i_cannot_alter();
}