bug with LimitedFraction and MathQuill

[Alex-Jordan]

With the MWE below, it behaves as expected in 2.19. But in develop, when you submit the answer -1/2 with MathQuill, the answer ends up submitted as -(1/2) and is not accepted.

DOCUMENT();

loadMacros(qw(PGstandard.pl PGML.pl contextFraction.pl));

Context("LimitedFraction");
$answer = Fraction(-1/2);

BEGIN_PGML
[`[$answer]={}`][_]{$answer}
END_PGML

ENDDOCUMENT();

[drgrice1]

What MathQuill does with this hasn't changed from 2.19 to now. I suspect this is another issue with the contextFraction.pl changes, and using the contextExtensions.pl macro.

[somiaj]

I am able to fix the issue with reverting the following change to the LimitedFraction context, by reverting the change to using an extension of LimitedNumeric. It seems that LimitedNumeric removes ( parens, which is what is causing the error. I tried to just add $context->parens->redefine('(');, but that didn't work. Reverting defining the context to how it was defined before using a copy of LimitedNumeric fixed the issue for me. I have a feeling there is a better way to do this though since I'm not extending LimitedNumeric, directly.

diff --git a/macros/contexts/contextFraction.pl b/macros/contexts/contextFraction.pl
index 3179d09d..49e8e029 100644
--- a/macros/contexts/contextFraction.pl
+++ b/macros/contexts/contextFraction.pl
@@ -345,8 +345,11 @@ sub Init {
        $context->{error}{msg}{"You are not allowed to type decimal numbers in this problem"} =
                "You are only allowed to enter fractions, not decimal numbers";
 
-       $context = $main::context{LimitedFraction} = context::Fraction::extending('LimitedNumeric');
+       $context = $main::context{LimitedFraction} = $context->copy;
        $context->{name} = "LimitedFraction";
+       $context->operators->undefine('+', '-', '*', '* ', '^', '**', 'U', '.', '><', 'u+', '!', '_', ',',);
+       $context->parens->undefine('|', '{', '[');
+       $context->functions->disable('All');
        $context->flags->set(
                strictFractions   => 1,
                allowMixedNumbers => 1,

[dpvc]

Here is a change that I think will resolve the issue while still using the LimitedNumeric context.

diff --git a/macros/contexts/contextFraction.pl b/macros/contexts/contextFraction.pl
index 112878a9..2aea9ee8 100644
--- a/macros/contexts/contextFraction.pl
+++ b/macros/contexts/contextFraction.pl
@@ -354,6 +354,7 @@ sub Init {
                showMixedNumbers  => 1,
        );
        $context->{cmpDefaults}{Fraction} = { studentsMustReduceFractions => 1 };
+       $context->parens->redefine('(');
 
        $context = $main::context{LimitedProperFraction} = $context->copy;
        $context->flags->set(requireProperFractions => 1);
@@ -673,7 +674,7 @@ our @ISA = ('context::Fraction::Class', 'Parser::UOP');
 sub _check {
        my $self = shift;
        $self->{hadParens} = 1 if $self->{op}{hadParens};
-       &{ $self->super('_check') }($self);
+       &{ $self->super('_check') }($self) unless $self->extensionClassMatch($self->{op}, 'FRACTION');
        $self->setExtensionClass('MINUS') if $self->{op}->class eq 'Number';
        $self->mutate;
 }

[Alex-Jordan]

Thanks @dpvc, that works for the two problems I know of where this issue had bubbled up.