Question

I’m working on a test framework in Perl. As part of the tests, I may need to add precondition or postcondition checks for any given test, but not necessarily for all of them. What I’ve got so far is something like:

eval '&verify_precondition_TEST$n'; print $@ if $@; 

Unfortunately, this outputs ‘Undefined subroutine &verify_precondition_TEST1 called at …’ if the function does not exist.

How can I determine ahead of time whether the function exists, before trying to call it?

Answer 1

With defined:

if (eval 'defined(&verify_precondition_TEST$n)') {     eval '&verify_precondition_TEST$n';     print $@ if $@; } else {     print 'verify_precondition_TEST$n does not exist\n'; } 

EDIT: hmm, I only thought of eval as it was in the question but with symbolic references brought up with Leon Timmermans, couldn’t you do

if (defined(&{'verify_precondition_TEST$n'}) {     &{'verify_precondition_TEST$n'};     print $@ if $@; } else {     print 'verify_precondition_TEST$n does not exist\n'; } 

even with strict?