Global symbol "$EVAL_ERROR" requires explicit package name

[Cev Ing]

When I try the example from the synopsis of Scanless::R, I get the error

Global symbol "$EVAL_ERROR" requires explicit package name

https://metacpan.org/pod/distribution/Marpa-R2/pod/Scanless/R.pod#Synopsis

Is it necessary to import the variable from a Marpa package?

[Ruslan Shvedov]

Nope, you an add use English; -- it's a long name for eval's return value. 

But then you'll have to add the grammar and input string.

If you need a full runnable example, the code from https://metacpan.org/pod/distribution/Marpa-R2/pod/Scanless.pod#Synopsis will serve you better.

 

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[Jeffrey Kegler]

Also, one feature of Marpa is that *all* examples of code are in the test suite -- so they all do actually run in some context.

The one for the Scanless::R synopsis is in t/sl_gyn.t.  Note that, in the test suite, the context may be some intricate framework required by the testing, but it nonetheless will be a context in which the example was made to work.

[Cev Ing]

Am Donnerstag, 26. November 2015 17:12:10 UTC+1 schrieb rns:

Nope, you an add use English; -- it's a long name for eval's return value.

Ah thanks I got it. Never used the English packages.

 

If you need a full runnable example, the code from https://metacpan.org/pod/distribution/Marpa-R2/pod/Scanless.pod#Synopsis will serve you better.

I was looking for an example with actions. The example of Scannless just blesses and traverses the blessed objects.

[Ruslan Shvedov]

Then, per Jeffrey's advice, you can adapt code from https://github.com/jeffreykegler/Marpa--R2/blob/master/cpan/t/sl_gsyn.t

[Jeffrey Kegler]

For your specific issue, two solutions are

1.) Add "use English qw( -no_match_vars );" to your Perl script.  Make sure to use the form I just quoted, in order to avoid an efficiency issue.

2.) Translate all the "Englished" vars to their "Pure Perl" form.   There is a man page with the translations.  For example, $EVAL_ERROR translates to $@ in pure Perl.

I use the "Englished" forms in the examples, because they are supposed to be easier to read, and "English" is a core module.