perl syntax check

H

Helmut Richter

I'd like to do a perl syntax check as distinct from an execution. I am
well aware that there are many errors that cannot be found without
execution but I'd like to first remove the errors that can be found
without execution and *then* execute the script. My attempt was using the
-wc flag, but this has no effect whatsoever.
perl -wc ali.pl
Click to expand...
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 362.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 363.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 365.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 419.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 432.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
Status: 500
Content-type: text/html

<h1>Software error:</h1>
. . .


The script is intended as CGI Script. The format of the error messages, to
wit the same format as web server log entries and a status code 500, is
hardly conceivable as pure syntax error messages from perl. Rather, the
code must have been executed somehow. How could I prevent that?
 
T

Tim McDaniel

Quoth Helmut Richter said:
I'd like to do a perl syntax check as distinct from an execution. I
am well aware that there are many errors that cannot be found
without execution but I'd like to first remove the errors that can
be found without execution and *then* execute the script. My
attempt was using the -wc flag, but this has no effect whatsoever.
Click to expand...

It does. -c makes perl stop at the end of the main compile-time
phase, exactly at the point where it stops invoking CHECK blocks and
starts invoking INIT blocks.
perl -wc ali.pl
Click to expand...
[Fri Jan 20 16:51:56 2012] ali.pl: Variable "$body" is not imported at
ali.pl line 362.
[Fri Jan 20 16:51:56 2012] ali.pl: (Did you mean &body instead?)
Status: 500
Content-type: text/html

<h1>Software error:</h1>
. . .

The script is intended as CGI Script. The format of the error
messages, to wit the same format as web server log entries and a
status code 500, is hardly conceivable as pure syntax error
messages from perl. Rather, the code must have been executed
somehow. How could I prevent that?
Click to expand...

'use' statements happen at compile time. (That's the point.) This
means that any code executed as part of a module's ->import method
will be run even under -c. Presumably you are using some module
(CGI::Carp?) that hooks into $SIG{__WARN__} (or something similar)
and changes the warning format: the only way to stop that code from
running is to comment out the 'use' statement.
Click to expand...

I don't think the major problem is the log line format. His problem
statement is not so clear, but I think the problem is in the lines you
trimmed some of and that I restored above:

Status: 500
Content-type: text/html

<h1>Software error:</h1>
. . .

That appears to be running the actual code, despite (as your write)
As a matter of good style, modules shouldn't do anything 'important'
(open files, connect to databases, print output...) during compile
time, but should wait to be asked. Since this *is* just a matter of
style, though, there is nothing preventing modules from ignoring it
if they choose to.
Click to expand...

Just to be sure: Helmut, how is the CGI output being generated?
Surely it isn't
BEGIN {
print standard_HTTP_header();
print "<html>\n<head>\n"; ...
}
.... or is it?
 
H

Helmut Richter

Assuming this is CGI::Carp, that output is almost certainly coming from
the __DIE__ handler. This is running because perl is dieing at compile
time, due to there being a fatal compile-time error (probably a syntax
error) somewhere in the code. If the code were correct it would stop
without producing any output.
Click to expand...

Yes, it is certainly from "use CGI::Carp qw(fatalsToBrowser);" which I use
while debugging -- later without the fatalsToBrowser. It works fine for
errors at run time but not at compile time. It would be nice it did, just
sending the syntax errors to the browser screen, but it doesn't: the
browser gets an error 500 and the syntax errors go to the Nirwana.

Commenting out this line when doing syntax checks only is an acceptable
option.

Thank you.
 
W

Willem

Helmut Richter wrote:
) On Fri, 20 Jan 2012, Ben Morrow wrote:
)
)> Assuming this is CGI::Carp, that output is almost certainly coming from
)> the __DIE__ handler. This is running because perl is dieing at compile
)> time, due to there being a fatal compile-time error (probably a syntax
)> error) somewhere in the code. If the code were correct it would stop
)> without producing any output.
)
) Yes, it is certainly from "use CGI::Carp qw(fatalsToBrowser);" which I use
) while debugging -- later without the fatalsToBrowser. It works fine for
) errors at run time but not at compile time. It would be nice it did, just
) sending the syntax errors to the browser screen, but it doesn't: the
) browser gets an error 500 and the syntax errors go to the Nirwana.

Odd, it's supposed to send the compile time errors as well.
Have you turned off 'pretty errors' in your browser?


SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT
 
D

David Combs

Odd, it's supposed to send the compile time errors as well.
Have you turned off 'pretty errors' in your browser?
Click to expand...

What browsers have a "pretty errors" feature?

Would emacs be one of them?

Thanks,

David
 

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