Variable adjacent to code substitution in TEXT causes hardcopy error. about pg

[apizer]

This is not an old issue. It is new to WW2.18. It breaks one of the oldest WW problems (Problem 2 in Set 0) but I thought the problem was corrupted and fixed it by accident. Another problem actually was corrupted (missing ;) I could not get the minimal problem above to work, but the following (please forgive my old technique) works in WW2.17 but fails in WW2.18.

DOCUMENT();
loadMacros("PGstandard.pl");
BEGIN_TEXT
Enter 1:
$BR{ ans_rule(1) }

END_TEXT
$ans =1;
ANS(std_num_cmp($ans));

ENDDOCUMENT();

Note that in the installation guide I said:
Note that most of these sets date from the early days of WeBWorK in the 1990's and the problems they contain, while they still work, are not examples of current good programing practices. For current programing methods, look at e.g. https://webwork.maa.org/wiki/Category:PGM. Further, Problem 12 in setMAAtutorial (file htmllinksexample.pg) contains a simple error which is typical of errors you might make in authoring your own problems. WeBWorK tries to tell you what the error is and you can use the Edit button to edit and save the problem. Problem 2 in set0 (file prob1a.pg) contains more subtle errors. The Open Problem Library (OPL) contains over 37,000 problems the vast majority of which are error free.

[drgrice1]

This seems to be due to #863. If you add a space in the TeX string on line 319 of PGbasicmacros.pl, then hardcopy generation succeeds. However, it also adds a space in the output which is not desired. This seems to be another case of EV3P parsing something in an odd way.

[Alex-Jordan]

Quick note that my MWE was missing MathObjects.pl.

DOCUMENT();
loadMacros("PGstandard.pl", "MathObjects.pl");
BEGIN_TEXT

$DOLLAR\{ ans_rule(1) \}

END_TEXT
ANS(Real(1)->cmp);
ENDDOCUMENT();

[drgrice1]

So what is happening is that "<<END_OF_EVALUATION_STRING\n$DOLLAR{\\answerRule[AnSwEr0001]{3}}\nEND_OF_EVALUATION_STRING\n" is being passed to PG_restricted_eval by the EV3P method. So that is the perl code

<<END_OF_EVALUATION_STRING
$DOLLAR{\\answerRule[AnSwEr0001]{3}}
END_OF_EVALUATION_STRING

Perl is interpreting that to mean the hash key of the %DOLLAR hash indexed by \\answerRule[AnSwEr0001]{3}. Since the %DOLLAR hash is not defined, it is an error.

[drgrice1]

Yeah, I added MathObjects.pl.

[drgrice1]

It seems that if you change line 319 to TeX => "\\mbox{\\answerRule[$name]{$tcol}}" it fixes the problem. This seems like it should work. Do you see any problems with that? Note that all of the answer rule methods that add this \\answerRule in this way will need to be fixed.

[drgrice1]

Note that the \\mbox addition also works with Library/Indiana/Indiana_setSeries5IntegralTest/ur_sr_5_11.pg (the problem @pstaabp mentioned in #863 that results in the answer rule output being placed inside the option brackets of an \item.

[Alex-Jordan]

I'm not getting this to happen on develop. #915 and related PRs for develop fixed this.