use Time::Piece

[Martin McCormick]

I can not seem to send Time::Piece any syntax it likes.

The file I am reading sends a time stamp that should
conform to RFC822 date stamps. An example of a stamp follows:

main::(lwx:204): my @obtime = split( /\,+/, $data->{observation_time_
rfc822} );
DB<2> print $obtime[1]
30 Oct 2018 20:53:00 -0500
DB<2> n
main::(lwx:205): my $t1 = Time::Piece->strptime( '$obtime[1]', '%D %b
%H:%M:%S %z' );
DB<2> n
Error parsing time at /usr/lib/i386-linux-gnu/perl/5.24/Time/Piece.pm line 481.
at /usr/lib/i386-linux-gnu/perl/5.24/Time/Piece.pm line 481.
Time::Piece::strptime("Time::Piece", "\$obtime[1]", "%D %b %H:%M:%S %z")
called at lwx line 205

The code that caused all that follows:

my @obtime = split( /\,+/, $data->{observation_time_rfc822} );
my $t1 = Time::Piece->strptime( '$obtime[1]', '%D %b %H:%M:%S %z' );

Another thing I tried was just
my $t1 = Time::Piece->strptime( '$obtime[1]', '%z' );

The man page for strptime lists all the possible %flags
one can send and the last one is %z for RFC822

%z An RFC-822/ISO 8601 standard timezone specification.

I was not sure if that meant it would pull in all the fields
shown above. If it had, I wouldn't be posting this message so I
tried the longer form

my $t1 = Time::Piece->strptime( '$obtime[1]', '%D %b %H:%M:%S %z' );

There is that -500 offset from utc, soon to become a -600 this
Sunday.

The following code will demonstrate the only outcome I have been
able to get. Those of you who followed earlier messages in the
thread about time stamps will recognise this code which now has a
few more lines and the data dumper is commented out but it
demonstrates what is happening.

If there is some way to see what Time::Piece thinks I am
trying to tell it to do then one might be able to figure out what
is wrong but a miss is the same as close so I can't tell if I am
getting warm.

Thanks for any ideas.

Martin McCormick

Code follows:

#!/usr/bin/perl -w
use strict;
use warnings::unused;
use Data::Dumper;
use XML::Simple;
use File::Basename;
use Cwd;
use File::stat;
use Time::Local;
use Time::Piece;
my $homedir = "/tmp";
my @t = localtime(time);
my $utcsec = timelocal(@t);
my $wxfile = 'display.php?stid=KSWO';

#I want that file to end up in a specific directory so:
my $wxpath = $homedir . "/" . $wxfile;
my $day = 86400; #seconds
my $hour = 3600;
my $gmt_offset_in_seconds = timegm(@t) - timelocal(@t);
my $tzoffset = $gmt_offset_in_seconds / 3600;

#many thanks to whoever wrote the quick way to determine TZ
#offset from utc

my $wxlast_update_time;

#Grab conditions from NOAA if the file is stale or missing.
if ( !stat($wxpath) ) { #The file is not there.
system(
"curl -s -o $wxpath 'http://w1.weather.gov/xml/current_obs/$wxfile'");

#Change the mtime to a quarter past last hour.
my $when = timelocal( 0, 15, $t[2], $t[3], $t[4], ( $t[5] - 100 ) );
utime $when, $when, "$wxpath";
} #The file is not there.
else { #what normally happens
my $wxstatRef = stat($wxpath);
$wxlast_update_time = $wxstatRef->mtime();
my $wxage = ( $utcsec - $wxlast_update_time );
if ( $wxage >= $hour ) { #File needs to be refreshed.

#The file should not be more than 3600 seconds old.
system(
"curl -s -o $wxpath 'http://w1.weather.gov/xml/current_obs/$wxfile'"
);

#Change the mtime to a quarter past.
my $when = timelocal( 0, 15, $t[2], $t[3], $t[4], ( $t[5] - 100 ) );
utime $when, $when, "$wxpath";
} #File needs to be refreshed.
} #what normally happens

# create object
my $xml = new XML::Simple;

# read XML file
my $data = $xml->XMLin("$wxpath");

#print Dumper($data);

my @obtime = split( /\,+/, $data->{observation_time_rfc822} );
my $t1 = Time::Piece->strptime( '$obtime[1]', '%D %b %H:%M:%S %z' );
exit(0);

[Uri Guttman]

On 10/30/18 11:24 PM, Martin McCormick wrote:
> I can not seem to send Time::Piece any syntax it likes.
>
> The file I am reading sends a time stamp that should
> conform to RFC822 date stamps. An example of a stamp follows:
>
> main::(lwx:204): my @obtime = split( /\,+/, $data->{observation_time_
> rfc822} );
> DB<2> print $obtime[1]
> 30 Oct 2018 20:53:00 -0500

whenever i print stuff for debugging i put it in [] or similar so i can
see white space or other odd things.

try print "[$obtime[1]]" and see what is really there.

> DB<2> n
> main::(lwx:205): my $t1 = Time::Piece->strptime( '$obtime[1]', '%D %b
> %H:%M:%S %z' );

well, that will always fail. you are parsing the actual string
$obtime[1] and not its value. single quote are not allowing any
interpolation. you don't even need quotes to pass a scalar value and it
is usually a bug.

> DB<2> n
> Error parsing time at /usr/lib/i386-linux-gnu/perl/5.24/Time/Piece.pm line 481.
> at /usr/lib/i386-linux-gnu/perl/5.24/Time/Piece.pm line 481.
> Time::Piece::strptime("Time::Piece", "\$obtime[1]", "%D %b %H:%M:%S %z")
> called at lwx line 205

similar bug. you escape the $ so the timestamp value is not
interpolated. you are parsing the wrong  string.

> If there is some way to see what Time::Piece thinks I am
> trying to tell it to do then one might be able to figure out what
> is wrong but a miss is the same as close so I can't tell if I am
> getting warm.

just stop with the extra quotes (single or double). just pass $obtime[1]
to strptime. i am guessing you are passing in Time::Piece as the class
in what would be an OO call. stick to the normal OO style there.


uri

[Martin McCormick]

Uri Guttman <u...@stemsystems.com> writes:
> whenever i print stuff for debugging i put it in [] or similar so i can
> see
> white space or other odd things.
>
>
> try print "[$obtime[1]]" and see what is really there.

DB<2> print "[$obtime[1]]"
[ 31 Oct 2018 06:53:00 -0500]

I do believe that the leading white space before the 3 should not
be there.

#get rid of leading spaces.
$obtime[1] =~ s/^\s+//;
#get rid of trailing spaces.
$obtime[1] =~ s/\s+$//;

DB<2> print "[$obtime[1]]"

[31 Oct 2018 06:53:00 -0500]

One of the oldest admonitions in the book says "Never trust data."

That leading space came from the split of a , separated
string and it completely got by me.

I'd like to say that it's working but not yet. There seems to be
nothing wrong with the string now.

my $t1 = Time::Piece->strptime("$obtime[1], %d %b %Y %H:%M:%S %z");

Still the parse error.

Right now, I do have both

use Time::Local;
use Time::Piece;

in the program and Time::Piece is supposed to replace many of the
functions of Time::Local. If I comment out Time::Local, a
reference to gntime breaks.

Could this be causing Time::Piece not to work?

Martin McCormick

[Sam]

None of your arguments are right. For one, you are using the '%D' flag
which is the same as saying '%m/%d/%y'

This works fine from a quick command line test:
perl -e 'use Time::Piece; $t = "30 Oct 2018 20:53:00 -0500"; print
Time::Piece->strptime( $t, "%d %b %Y %H:%M:%S %z" );'

Wed Oct 31 01:53:00 2018

But notice since you specified '%z', that that offset was added to the
returned time... That might be what you want, or it might not be. And
also note Time::Piece->strptime returns an object that is set to UTC
whereas localtime->strptime returns an object not in UTC. If you really
want to get crazy with parsing times, DateTime is usually recommended:
https://metacpan.org/pod/DateTime or just
https://metacpan.org/pod/DateTime::Format::Strptime

--Samuel Smith

[Martin McCormick]

Jim Gibson <jimsg...@gmail.com> writes:
> On Oct 31, 2018, at 1:29 PM, Martin McCormick <mart...@suddenlink.net>

> wrote:

> > my $t1 = Time::Piece->strptime("$obtime[1], %d %b %Y %H:%M:%S %z”);
>

> strptime is a method with two arguments: string to be parsed, format to
> be used for parsing. You have one argument: a double-quoted string.
>
> my $t1 = Time::Piece->strptime($obtime[1], "%d %b %Y %H:%M:%S %z”);

Thank you! I forgot to keep that in mind. As I kept trying
to get it to work and ended up with the , that separates the
arguments inside the whole string. I may have even had it right
once but that may have been when at least one %variable was set
to the wrong case which would have made the correct format also
fail but for different reasons. %d should have been the first
field which is the day of the month and instead, I had %D which
is a specific United States way of expressing a date

I know we all have our stupid moments but sometimes, I wish
I didn't have so many.

Now, $t1 shows a nice representation of the UTC date that
the web server stamped the XML file with.

Martin McCormick

[Martin McCormick]

Sam <pe...@net153.net> writes:
>
>
>
> None of your arguments are right. For one, you are using the '%D' flag
> which is the same as saying '%m/%d/%y'
>
>
> This works fine from a quick command line test:
>
> perl -e 'use Time::Piece; $t = "30 Oct 2018 20:53:00 -0500"; print
> Time::Piece->strptime( $t, "%d %b %Y %H:%M:%S %z" );'
>
>
> Wed Oct 31 01:53:00 2018
>
>
> But notice since you specified '%z', that that offset was added to the
> returned time... That might be what you want, or it might not be. And also
> note Time::Piece->strptime returns an object that is set to UTC whereas
> localtime->strptime returns an object not in UTC. If you really want to
> get
> crazy with parsing times, DateTime is usually recommended: https://
> metacpan.org/pod/DateTime or just https://metacpan.org/pod/
> DateTime::Format::Strptime
>
>
> --Samuel Smith

Thank you. This turned out to be a comedy of errors on
my part. It seems I may have stumbled across the correct way to
call the function but didn't realize it because of the wrong
arguments you saw. I figured the %D issue out but, by that time,
I had messed around with things long enough that I forgot the ,
which separates the two arguments to that method must not be part
of the quoted string so even when the %variables were right, the
call would never work the way I had it.

Another poster pointed this out and it now works fine.

Thanks to all who helped.

Martin McCormick