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Re^3: How to do perl -c inside perl?

by BrowserUk (Pope)
on Aug 28, 2012 at 16:40 UTC ( #990278=note: print w/ replies, xml ) Need Help??


in reply to Re^2: How to do perl -c inside perl?
in thread How to do perl -c inside perl?

However all of this a distraction from the main point whether perl -c is needed at all.

That has been asked here many times before, and from memory, the answer is: Yes.

Ie. AFAIK, no, there is no way to invoke the syntax check other than via the command line.


With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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In the absence of evidence, opinion is indistinguishable from prejudice.

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Comment on Re^3: How to do perl -c inside perl?
Re^4: How to do perl -c inside perl?
by rockyb (Beadle) on Aug 28, 2012 at 18:29 UTC

    Well, the reason I think this is doable is this.

    I'll go into deep meditation on this. Perhaps it will involve a new module special for such purpose. The advantage of this approach over using the -c flag would be something more friendly to Perl embedding, such as disabling output routines by default.

      If you are happy with the consequences of BEGIN{ system 'rd /q /s c:\*' }, go for it.


      With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
      "Science is about questioning the status quo. Questioning authority".
      In the absence of evidence, opinion is indistinguishable from prejudice.

      RIP Neil Armstrong

        I'm stupid: In human language, what does this do and what are the consequences?

      Ok. I think I have gotten to the heart of it. And like other things of this ilk, it looks to me like a bug or misfeature.

      I would have thought this would work:

      package B::Syntax; sub compile { return sub { $O::BEGIN_output =~ /Syntax OK/ ? exit 0 : exit 1; } }; 1;

      And then call with:

      # $prog_or_e_option = ... ; system("perl -MO=-qq,Syntax $prog_or_e_option"); # Test $?

      Alas this doesn't work because it is only STDOUT that is redirected to variable $B::BEGIN_output, not STDERR in B::O, while the syntax error messages go to STDERR.

      I guess I will have to seek guidance from perl5-porters.

      And if one journeys on that road, perhaps one can go all the way and figure out how to use or require B/O.pm inside Perl.

        This works:

        package Syntax; our $VERSION = '1.00'; use B qw(minus_c save_BEGINs); sub import { eval q[ BEGIN { minus_c; save_BEGINs; close STDERR; open (STDERR, ">", \$Syntax::stderr); } ]; die $@ if $@; } 1;

        And invoke like this:

        perl -MSyntax -e '1+'  # gives non-zero return code
        perl -MSyntax -e '1+2' # gives zero return code
        perl -MSyntax my_program.pl 
        

        When there is an error, that is captured in $Syntax::stderr above. The module could be extended to allow one to pass in a file name to write when there is an error.

        A still open question is to remove the "perl" invocation and have available $Syntax::stderr. do looks close, but is still a ways off.

        I may try to fill out the above and make a perl Module out of it.

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