How can I handle a perl constructor that dies?

Question

Code snippet:

my $tz = DateTime::TimeZone->new(name => 'America/San_Francisco');

This immediately dies because America/San_Francisco is not a recognized timezone.

The following message is printed:

The timezone 'America/San_Francisco' could not be loaded, or is an invalid name.

I would like to handle this error and print additional info for the user before the script exits. I tried using unless, but no luck catching the die.

How can this be done?

mpapec · Accepted Answer · 2017-01-10 07:43:40Z

5

Use eval { ... } and $@ to trap and manage fatal errors.

my $tz = eval { DateTime::TimeZone->new(name => 'America/San_Francisco') }; if (!$tz) { if ($@ =~ /The timezone .* could not be loaded/) { warn "Choose a timezone from ", "https://en.wikipedia.org/wiki/List_of_tz_database_time_zones#List"; } else { warn "Error in DateTime::TimeZone constructor: $@"; } exit 1; }

edited Jan 10, 2017 at 7:43

mpapec

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answered Jan 9, 2017 at 17:21

mob

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5 Comments

Jonathan Cross Over a year ago

This almost works, but gives me a strange error:

Choose a timezone from https://en.wikipedia.org/wiki/List_of_tz_database_time_zones#List at ./test-die.pl line 6, <DATA> line 1.

choroba Over a year ago

my $tz; eval { $tz = .... ; 1 } or do { if ($@ =~ is safer. $@ might be clobbered in some Perl versions. See Try::Tiny and Bug in eval in pre-5.14.

Matt Jacob Over a year ago

@JonathanCross Add a \n to the end of the string to prevent the location from being included.

AKHolland Over a year ago

Try::Tiny is safer than evals.

ikegami Over a year ago

@choroba, my $tz = eval { ... } or do { ... }; would suffice since DateTime::TimeZone->new always returns a true value.

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