develooper Front page | perl.perl5.porters | Postings from July 2020

Re: Perl 7 - updates

Thread Previous | Thread Next
Darren Duncan
July 4, 2020 03:10
Re: Perl 7 - updates
Message ID:
But my key point is that Perl doesn't require the shebang line and it will 
interpret the Perl code without there being one. -- Darren Duncan

On 2020-07-03 7:21 p.m., David Mertens wrote:
> Perl does not idly ignore the first line if it is a shebang line. In fact, it 
> examines the shebang line for command line switches and enables them.
> On Fri, Jul 3, 2020, 9:37 PM Darren Duncan wrote:
>     On 2020-07-03 5:35 p.m., Todd Rinaldo wrote:
>      > As far as I understand, the Perl parser doesn't start parsing the code
>     until it sees #!/usr/bin/perl in which case you just put use v7 after that line.
>     I'm quite sure that is wrong.
>     The only real purpose of the shebang line is to help a shell know to run Perl
>     and not say Python when you just say something like this:
>         ./ <>
>     Whereas, once Perl is actually running and given the file, that line has no
>     purpose and is just a completely optional comment.
>     And so, if you run a program like this instead:
>         perl <>
>     Then it will just work even with no shebang line in the file.
>     In fact I've heard it often argued that having a shebang line for the most part
>     is an obsolete notion and it is best to NOT have it, especially as in the
>     general case what it says is completely wrong.  What if your Perl lives
>     somewhere else?  Or what if you're running Windows?
>     Although a lot of that is addressed by using a different more adaptable shebang
>     line like either of these:
>         #!perl
>         #!which perl
>         #!/usr/bin/which perl
>     But still, at the very least, only the main program has any business containing
>     a shebang line and any library files just called by other Perl files with "use"
>     etc have no reason to contain them.
>     -- Darren Duncan

Thread Previous | Thread Next Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at | Group listing | About