How can I compile a Perl script inside a running Perl session?

Question

I have a Perl script that takes user input and creates another script that will be run at a later date. I'm currently going through and writing tests for these scripts and one of the tests that I would like to perform is checking if the generated script compiles successfully (e.g. perl -c <script>.) Is there a way that I can have Perl perform a compile on the generated script without having to spawn another Perl process? I've tried searching for answers, but searches just turn up information about compiling Perl scripts into executable programs.

Answer 1

Compiling a script has a lot of side-effects. It results in subs being defined. It results in modules being executed. etc. If you simply want to test whether something compiles, you want a separate interpreter. It's the only way to be sure that one testing one script doesn't cause later tests to give false positives or false negatives.

Answer 2

To execute dynamically generated code, use eval function:

my $script = join /\n/, <main::DATA>;
eval($script);   # 3

__DATA__

my $a = 1;
my $b = 2;
print $a+$b, "\n";

However if you want to just compile or check syntax, then you will not be able to do it within same Perl session.

Function syntax_ok from library Test::Strict run a syntax check by running perl -c with an external perl interpreter, so I assume there is no internal way.

Only work-around that may work for you would be:

my $script = join /\n/, <main::DATA>; 
eval('return;' . $script); 
warn $@ if $@;   # syntax error at (eval 1) line 3, near "1
                 # my "

__DATA__ 

my $a = 1
my $b = 2; 
print $a+$b, "\n";

In this case, you will be able to check for compilation error(s) using $@, however because the first line of the code is return;, it will not execute.

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Note: Thanks to user mob for helpfull chat and code correction.