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Revision 685 - (download) (as text) (annotate)
Mon Jan 6 19:41:44 2003 UTC (10 years, 5 months ago) by sh002i
File size: 20301 byte(s)
DONE	results table
		part(or blank)/entered/preview/result/messages
		don't show messages unless there are some
-sam

    1 ################################################################################
    2 # WeBWorK mod_perl (c) 2000-2002 WeBWorK Project
    3 # $Id$
    4 ################################################################################
    5 
    6 package WeBWorK::ContentGenerator::Problem;
    7 
    8 =head1 NAME
    9 
   10 WeBWorK::ContentGenerator::Problem - Allow a student to interact with a problem.
   11 
   12 =cut
   13 
   14 use strict;
   15 use warnings;
   16 use base qw(WeBWorK::ContentGenerator);
   17 use CGI qw();
   18 use File::Temp qw(tempdir);
   19 use WeBWorK::Form;
   20 use WeBWorK::PG;
   21 use WeBWorK::PG::IO;
   22 use WeBWorK::Utils qw(writeLog encodeAnswers decodeAnswers ref2string);
   23 
   24 ############################################################
   25 #
   26 # user
   27 # key
   28 #
   29 # displayMode
   30 # showOldAnswers
   31 # showCorrectAnswers
   32 # showHints
   33 # showSolutions
   34 #
   35 # AnSwEr# - answer blanks in problem
   36 #
   37 # redisplay - name of the "Redisplay Problem" button
   38 # submitAnswers - name of "Submit Answers" button
   39 #
   40 ############################################################
   41 
   42 sub pre_header_initialize {
   43   my ($self, $setName, $problemNumber) = @_;
   44   my $courseEnv = $self->{courseEnvironment};
   45   my $r = $self->{r};
   46   my $userName = $r->param('user');
   47 
   48   ##### database setup #####
   49 
   50   my $cldb   = WeBWorK::DB::Classlist->new($courseEnv);
   51   my $wwdb   = WeBWorK::DB::WW->new($courseEnv);
   52   my $authdb = WeBWorK::DB::Auth->new($courseEnv);
   53 
   54   my $user            = $cldb->getUser($userName);
   55   my $set             = $wwdb->getSet($userName, $setName);
   56   my $problem         = $wwdb->getProblem($userName, $setName, $problemNumber);
   57   my $psvn            = $wwdb->getPSVN($userName, $setName);
   58   my $permissionLevel = $authdb->getPermissions($userName);
   59 
   60   ##### form processing #####
   61 
   62   # set options from form fields (see comment at top of file for names)
   63   my $displayMode        = $r->param("displayMode")        || $courseEnv->{pg}->{options}->{displayMode};
   64   my $redisplay          = $r->param("redisplay");
   65   my $submitAnswers      = $r->param("submitAnswers");
   66   my $previewAnswers     = $r->param("previewAnswers");
   67 
   68   # coerce form fields into CGI::Vars format
   69   my $formFields = { WeBWorK::Form->new_from_paramable($r)->Vars };
   70 
   71   ##### permissions #####
   72 
   73   # what does the user want to do?
   74   my %want = (
   75     showOldAnswers     => $r->param("showOldAnswers")     || $courseEnv->{pg}->{options}->{showOldAnswers},
   76     showCorrectAnswers => $r->param("showCorrectAnswers") || $courseEnv->{pg}->{options}->{showCorrectAnswers},
   77     showHints          => $r->param("showHints")          || $courseEnv->{pg}->{options}->{showHints},
   78     showSolutions      => $r->param("showSolutions")      || $courseEnv->{pg}->{options}->{showSolutions},
   79     recordAnswers      => $r->param("recordAnswers")      || 1,
   80   );
   81 
   82   # are certain options enforced?
   83   my %must = (
   84     showOldAnswers     => 0,
   85     showCorrectAnswers => 0,
   86     showHints          => 0,
   87     showSolutions      => 0,
   88     recordAnswers      => mustRecordAnswers($permissionLevel),
   89   );
   90 
   91   # does the user have permission to use certain options?
   92   my %can = (
   93     showOldAnswers     => 1,
   94     showCorrectAnswers => canShowCorrectAnswers($permissionLevel, $set->answer_date),
   95     showHints          => 1,
   96     showSolutions      => canShowSolutions($permissionLevel, $set->answer_date),
   97     recordAnswers      => canRecordAnswers($permissionLevel, $set->open_date, $set->due_date,
   98       $problem->max_attempts, $problem->num_correct + $problem->num_incorrect + 1),
   99       # num_correct+num_incorrect+1 -- as this happens before updating $problem
  100   );
  101 
  102   # final values for options
  103   my %will;
  104   foreach (keys %must) {
  105     $will{$_} = $can{$_} && ($want{$_} || $must{$_});
  106   }
  107 
  108   ##### sticky answers #####
  109 
  110   if (not $submitAnswers and $will{showOldAnswers}) {
  111     # do this only if new answers are NOT being submitted
  112     my %oldAnswers = decodeAnswers($problem->last_answer);
  113     $formFields->{$_} = $oldAnswers{$_} foreach keys %oldAnswers;
  114   }
  115 
  116   ##### translation #####
  117 
  118   my $pg = WeBWorK::PG->new(
  119     $courseEnv,
  120     $user,
  121     $r->param('key'),
  122     $set,
  123     $problem,
  124     $psvn,
  125     $formFields,
  126     { # translation options
  127       displayMode     => $displayMode,
  128       showHints       => $will{showHints},
  129       showSolutions   => $will{showSolutions},
  130       refreshMath2img => $will{showHints} || $will{showSolutions},
  131       processAnswers  => 1,
  132     },
  133   );
  134 
  135   ##### fix hint/solution options #####
  136 
  137   $can{showHints}     &&= $pg->{flags}->{hintExists};
  138   $can{showSolutions} &&= $pg->{flags}->{solutionExists};
  139 
  140   ##### store fields #####
  141 
  142   $self->{cldb}            = $cldb;
  143   $self->{wwdb}            = $wwdb;
  144   $self->{authdb}          = $authdb;
  145 
  146   $self->{user}            = $user;
  147   $self->{set}             = $set;
  148   $self->{problem}         = $problem;
  149   $self->{permissionLevel} = $permissionLevel;
  150 
  151   $self->{displayMode}    = $displayMode;
  152   $self->{redisplay}      = $redisplay;
  153   $self->{submitAnswers}  = $submitAnswers;
  154   $self->{previewAnswers} = $previewAnswers;
  155   $self->{formFields}     = $formFields;
  156 
  157   $self->{want} = \%want;
  158   $self->{must} = \%must;
  159   $self->{can}  = \%can;
  160   $self->{will} = \%will;
  161 
  162   $self->{pg} = $pg;
  163 }
  164 
  165 sub if_warnings($$) {
  166   my ($self, $arg) = @_;
  167   return $self->{pg}->{warnings} ne "";
  168 }
  169 
  170 sub if_errors($$) {
  171   my ($self, $arg) = @_;
  172   return $self->{pg}->{flags}->{error_flag};
  173 }
  174 
  175 sub head {
  176   my $self = shift;
  177 
  178   return $self->{pg}->{head_text} if $self->{pg}->{head_text};
  179 }
  180 
  181 sub path {
  182   my $self = shift;
  183   my $args = $_[-1];
  184   my $setName = $self->{set}->id;
  185   my $problemNumber = $self->{problem}->id;
  186 
  187   my $ce = $self->{courseEnvironment};
  188   my $root = $ce->{webworkURLs}->{root};
  189   my $courseName = $ce->{courseName};
  190   return $self->pathMacro($args,
  191     "Home" => "$root",
  192     $courseName => "$root/$courseName",
  193     $setName => "$root/$courseName/$setName",
  194     "Problem $problemNumber" => "",
  195   );
  196 }
  197 
  198 sub siblings {
  199   my $self = shift;
  200   my $setName = $self->{set}->id;
  201   my $problemNumber = $self->{problem}->id;
  202 
  203   my $ce = $self->{courseEnvironment};
  204   my $root = $ce->{webworkURLs}->{root};
  205   my $courseName = $ce->{courseName};
  206 
  207   print CGI::strong("Problems"), CGI::br();
  208 
  209   my $wwdb = $self->{wwdb};
  210   my $user = $self->{r}->param("user");
  211   my @problems;
  212   push @problems, $wwdb->getProblem($user, $setName, $_)
  213     foreach ($wwdb->getProblems($user, $setName));
  214   foreach my $problem (sort { $a->id <=> $b->id } @problems) {
  215     print CGI::a({-href=>"$root/$courseName/$setName/".$problem->id."/?"
  216       . $self->url_authen_args}, "Problem ".$problem->id), CGI::br();
  217   }
  218 }
  219 
  220 sub nav {
  221   my $self = shift;
  222   my $args = $_[-1];
  223   my $setName = $self->{set}->id;
  224   my $problemNumber = $self->{problem}->id;
  225 
  226   my $ce = $self->{courseEnvironment};
  227   my $root = $ce->{webworkURLs}->{root};
  228   my $courseName = $ce->{courseName};
  229 
  230   my $wwdb = $self->{wwdb};
  231   my $user = $self->{r}->param("user");
  232 
  233   my @links = ("Problem List" => "$root/$courseName/$setName");
  234 
  235   my $prevProblem = $wwdb->getProblem($user, $setName, $problemNumber-1);
  236   my $nextProblem = $wwdb->getProblem($user, $setName, $problemNumber+1);
  237   unshift @links, "Previous Problem" => $prevProblem
  238     ? "$root/$courseName/$setName/".$prevProblem->id
  239     : "";
  240   push @links, "Next Problem" => $nextProblem
  241     ? "$root/$courseName/$setName/".$nextProblem->id
  242     : "";
  243 
  244   return $self->navMacro($args, @links);
  245 }
  246 
  247 sub title {
  248   my $self = shift;
  249   my $setName = $self->{set}->id;
  250   my $problemNumber = $self->{problem}->id;
  251 
  252   return "$setName : Problem $problemNumber";
  253 }
  254 
  255 sub body {
  256   my $self = shift;
  257 
  258   # unpack some useful variables
  259   my $r               = $self->{r};
  260   my $wwdb            = $self->{wwdb};
  261   my $set             = $self->{set};
  262   my $problem         = $self->{problem};
  263   my $permissionLevel = $self->{permissionLevel};
  264   my $submitAnswers   = $self->{submitAnswers};
  265   my $previewAnswers  = $self->{previewAnswers};
  266   my %will            = %{ $self->{will} };
  267   my $pg              = $self->{pg};
  268 
  269   ##### translation errors? #####
  270 
  271   if ($pg->{flags}->{error_flag}) {
  272     return translationError($pg->{errors}, $pg->{body_text});
  273   }
  274 
  275   ##### answer processing #####
  276 
  277   # if answers were submitted:
  278   if ($submitAnswers) {
  279     # store answers in DB for sticky answers
  280     my %answersToStore;
  281     my %answerHash = %{ $pg->{answers} };
  282     $answersToStore{$_} = $answerHash{$_}->{original_student_ans}
  283       foreach (keys %answerHash);
  284     my $answerString = encodeAnswers(%answersToStore,
  285       @{ $pg->{flags}->{ANSWER_ENTRY_ORDER} });
  286     $problem->last_answer($answerString);
  287     $wwdb->setProblem($problem);
  288 
  289     # store state in DB if it makes sense
  290     if ($will{recordAnswers}) {
  291       $problem->attempted(1);
  292       $problem->status($pg->{state}->{recorded_score});
  293       $problem->num_correct($pg->{state}->{num_of_correct_ans});
  294       $problem->num_incorrect($pg->{state}->{num_of_incorrect_ans});
  295       $wwdb->setProblem($problem);
  296       # write to the transaction log, just to make sure
  297       writeLog($self->{courseEnvironment}, "transaction",
  298         $problem->id."\t".
  299         $problem->set_id."\t".
  300         $problem->login_id."\t".
  301         $problem->source_file."\t".
  302         $problem->value."\t".
  303         $problem->max_attempts."\t".
  304         $problem->problem_seed."\t".
  305         $problem->status."\t".
  306         $problem->attempted."\t".
  307         $problem->last_answer."\t".
  308         $problem->num_correct."\t".
  309         $problem->num_incorrect
  310       );
  311     }
  312   }
  313 
  314   ##### output #####
  315 
  316   # attempt summary
  317   if ($submitAnswers or $will{showCorrectAnswers}) {
  318     # print this if user submitted answers OR requested correct answers
  319     print $self->attemptResults($pg, $submitAnswers, $will{showCorrectAnswers},
  320       $pg->{flags}->{showPartialCorrectAnswers}, 0);
  321   } elsif ($previewAnswers) {
  322     # print this if user previewed answers
  323     print $self->attemptResults($pg, 1, 0, 0, 1);
  324       # don't show correctness
  325       # don't show correct answers
  326   }
  327 
  328   # score summary
  329   my $attempts = $problem->num_correct + $problem->num_incorrect;
  330   my $attemptsNoun = $attempts != 1 ? "times" : "time";
  331   my $lastScore = int ($problem->status * 100) . "%";
  332   my ($attemptsLeft, $attemptsLeftNoun);
  333   if ($problem->max_attempts == -1) {
  334     # unlimited attempts
  335     $attemptsLeft = "unlimited";
  336     $attemptsLeftNoun = "attempts";
  337   } else {
  338     $attemptsLeft = $problem->max_attempts - $attempts;
  339     $attemptsLeftNoun = $attemptsLeft == 1 ? "attempt" : "attempts";
  340   }
  341   my $setClosedMessage;
  342   if (time < $set->open_date or time > $set->due_date) {
  343     $setClosedMessage = "This problem set is closed.";
  344     if ($permissionLevel > 0) {
  345       $setClosedMessage .= " Since you are a privileged user, additional attempts will be recorded.";
  346     } else {
  347       $setClosedMessage .= " Additional attempts will not be recorded.";
  348     }
  349   }
  350   print CGI::p(
  351     "You have attempted this problem $attempts $attemptsNoun.", CGI::br(),
  352     $problem->attempted
  353       ? "Your recorded score is $lastScore." . CGI::br()
  354       : "",
  355     "You have $attemptsLeft $attemptsLeftNoun remaining.", CGI::br(),
  356     $setClosedMessage,
  357   );
  358 
  359   print CGI::hr();
  360 
  361   # main form
  362   print
  363     CGI::startform("POST", $r->uri),
  364     $self->hidden_authen_fields,
  365     CGI::p(CGI::i($pg->{result}->{msg})),
  366     CGI::p($pg->{body_text}),
  367     CGI::p(
  368       CGI::submit(-name=>"submitAnswers", -label=>"Submit Answers"),
  369       CGI::submit(-name=>"previewAnswers", -label=>"Preview Answers"),
  370     ),
  371     $self->viewOptions(),
  372     CGI::endform();
  373 
  374   # feedback form
  375   my $ce = $self->{courseEnvironment};
  376   my $root = $ce->{webworkURLs}->{root};
  377   my $courseName = $ce->{courseName};
  378   my $feedbackURL = "$root/$courseName/feedback/";
  379   print
  380     CGI::startform("POST", $feedbackURL),
  381     $self->hidden_authen_fields,
  382     CGI::hidden("module",             __PACKAGE__),
  383     CGI::hidden("set",                $set->id),
  384     CGI::hidden("problem",            $problem->id),
  385     CGI::hidden("displayMode",        $self->{displayMode}),
  386     CGI::hidden("showOldAnswers",     $will{showOldAnswers}),
  387     CGI::hidden("showCorrectAnswers", $will{showCorrectAnswers}),
  388     CGI::hidden("showHints",          $will{showHints}),
  389     CGI::hidden("showSolutions",      $will{showSolutions}),
  390     CGI::p({-align=>"right"},
  391       CGI::submit(-name=>"feedbackForm", -label=>"Send Feedback")
  392     ),
  393     CGI::endform();
  394 
  395   # warning output
  396   if ($pg->{warnings} ne "") {
  397     print CGI::hr(), warningOutput($pg->{warnings});
  398   }
  399 
  400   # debugging stuff
  401   print
  402     CGI::hr(),
  403     CGI::h2("debugging information"),
  404     CGI::h3("form fields"),
  405     ref2string($self->{formFields}),
  406     CGI::h3("user object"),
  407     ref2string($self->{user}),
  408     CGI::h3("set object"),
  409     ref2string($set),
  410     CGI::h3("problem object"),
  411     ref2string($problem),
  412     CGI::h3("PG object"),
  413     ref2string($pg, {'WeBWorK::PG::Translator' => 1});
  414 
  415   return "";
  416 }
  417 
  418 ##### output utilities #####
  419 
  420 # this is used by ProblemSet.pm too, so don't fuck it up
  421 sub translationError($$) {
  422   my ($error, $details) = @_;
  423   return
  424     CGI::h2("Software Error"),
  425     CGI::p(<<EOF),
  426 WeBWorK has encountered a software error while attempting to process this problem.
  427 It is likely that there is an error in the problem itself.
  428 If you are a student, contact your professor to have the error corrected.
  429 If you are a professor, please consut the error output below for more informaiton.
  430 EOF
  431     CGI::h3("Error messages"), CGI::blockquote(CGI::pre($error)),
  432     CGI::h3("Error context"), CGI::blockquote(CGI::pre($details));
  433 }
  434 
  435 # this is used by ProblemSet.pm too, so don't fuck it up
  436 sub warningOutput($) {
  437   my $warnings = shift;
  438 
  439   return
  440     CGI::h2("Software Warnings"),
  441     CGI::p(<<EOF),
  442 WeBWorK has encountered warnings while attempting to process this problem.
  443 It is likely that this indicates an error or ambiguity in the problem itself.
  444 If you are a student, contact your professor to have the problem corrected.
  445 If you are a professor, please consut the error output below for more informaiton.
  446 EOF
  447     CGI::h3("Warning messages"),
  448     CGI::blockquote(CGI::pre($warnings)),
  449   ;
  450 }
  451 
  452 sub attemptResults($$$$$) {
  453   my $self = shift;
  454   my $pg = shift;
  455   my $showAttemptAnswers = shift;
  456   my $showCorrectAnswers = shift;
  457   my $showAttemptResults = $showAttemptAnswers && shift;
  458   my $showAttemptPreview = shift || 0;
  459   my $problemResult = $pg->{result}; # the overall result of the problem
  460   my @answerNames = @{ $pg->{flags}->{ANSWER_ENTRY_ORDER} };
  461 
  462   my $showMessages = $showAttemptAnswers && grep { $pg->{answers}->{$_}->{ans_message} } @answerNames;
  463 
  464   my $header = CGI::th("part");
  465   $header .= $showAttemptAnswers ? CGI::th("entered")  : "";
  466   $header .= $showAttemptPreview ? CGI::th("preview")  : "";
  467   $header .= $showCorrectAnswers ? CGI::th("correct")  : "";
  468   $header .= $showAttemptResults ? CGI::th("result")   : "";
  469   $header .= $showMessages       ? CGI::th("messages") : "";
  470   my @tableRows = ( $header );
  471   my $numCorrect;
  472   foreach my $name (@answerNames) {
  473     my $answerResult  = $pg->{answers}->{$name};
  474     my $studentAnswer = $answerResult->{student_ans}; # original_student_ans
  475     my $preview       = ($showAttemptPreview
  476                           ? $self->previewAnswer($answerResult)
  477           : "");
  478     my $correctAnswer = $answerResult->{correct_ans};
  479     my $answerScore   = $answerResult->{score};
  480     my $answerMessage = $showMessages ? $answerResult->{ans_message} : "";
  481 
  482     $numCorrect += $answerScore > 0;
  483     my $resultString = $answerScore ? "correct" : "incorrect";
  484 
  485     # get rid of the goofy prefix on the answer names (supposedly, the format
  486     # of the answer names is changeable. this only fixes it for "AnSwEr"
  487     $name =~ s/^AnSwEr//;
  488 
  489     my $row = CGI::td($name);
  490     $row .= $showAttemptAnswers ? CGI::td($studentAnswer) : "";
  491     $row .= $showAttemptPreview ? CGI::td($preview)       : "";
  492     $row .= $showCorrectAnswers ? CGI::td($correctAnswer) : "";
  493     $row .= $showAttemptResults ? CGI::td($resultString)  : "";
  494     $row .= $answerMessage      ? CGI::td($answerMessage) : "";
  495     push @tableRows, $row;
  496   }
  497 
  498   my $numCorrectNoun = $numCorrect == 1 ? "question" : "questions";
  499   my $scorePercent = int ($problemResult->{score} * 100) . "\%";
  500   my $summary = "On this attempt, you answered $numCorrect $numCorrectNoun out of "
  501     . scalar @answerNames . " correct, for a score of $scorePercent.";
  502   return CGI::table({-border=>1}, CGI::Tr(\@tableRows)) . CGI::p($summary);
  503 }
  504 
  505 sub viewOptions($) {
  506   my $self = shift;
  507   my $displayMode = $self->{displayMode};
  508   my %must = %{ $self->{must} };
  509   my %can  = %{ $self->{can}  };
  510   my %will = %{ $self->{will} };
  511 
  512   my $optionLine;
  513   $can{showOldAnswers} and $optionLine .= join "",
  514     "Show: &nbsp;",
  515     CGI::checkbox(
  516       -name    => "showOldAnswers",
  517       -checked => $will{showOldAnswers},
  518       -label   => "Saved answers",
  519     ), "&nbsp;&nbsp;";
  520   $can{showCorrectAnswers} and $optionLine .= join "",
  521     CGI::checkbox(
  522       -name    => "showCorrectAnswers",
  523       -checked => $will{showCorrectAnswers},
  524       -label   => "Correct answers",
  525     ), "&nbsp;&nbsp;";
  526   $can{showHints} and $optionLine .= join "",
  527     CGI::checkbox(
  528       -name    => "showHints",
  529       -checked => $will{showHints},
  530       -label   => "Hints",
  531     ), "&nbsp;&nbsp;";
  532   $can{showSolutions} and $optionLine .= join "",
  533     CGI::checkbox(
  534       -name    => "showSolutions",
  535       -checked => $will{showSolutions},
  536       -label   => "Solutions",
  537     ), "&nbsp;&nbsp;";
  538   $optionLine and $optionLine .= join "", CGI::br();
  539 
  540   return CGI::div({-style=>"border: thin groove; padding: 1ex; margin: 2ex"},
  541       "View equations as: &nbsp;",
  542     CGI::radio_group(
  543       -name    => "displayMode",
  544       -values  => ['plainText', 'formattedText', 'images'],
  545       -default => $displayMode,
  546       -labels  => {
  547         plainText     => "plain text",
  548         formattedText => "formatted text",
  549         images        => "images",
  550       }
  551     ), CGI::br(),
  552     $optionLine,
  553     CGI::submit(-name=>"redisplay", -label=>"Redisplay Problem"),
  554   );
  555 }
  556 
  557 sub previewAnswer($$) {
  558   my ($self, $answerResult) = @_;
  559   my $ce          = $self->{courseEnvironment};
  560   my $user        = $self->{user};
  561   my $set         = $self->{set};
  562   my $problem     = $self->{problem};
  563   my $displayMode = $self->{displayMode};
  564 
  565   # note: right now, we have to do things completely differently when we are
  566   # rendering math from INSIDE the translator and from OUTSIDE the translator.
  567   # so we'll just deal with each case explicitly here. there's some code
  568   # duplication that can be dealt with later by abstracting out tth/dvipng/etc.
  569 
  570   my $tex = $answerResult->{preview_latex_string};
  571 
  572   if ($displayMode eq "plainText") {
  573     return $tex;
  574   } elsif ($displayMode eq "formattedText") {
  575     my $tthCommand = $ce->{externalPrograms}->{tth}
  576       . " -L -f5 -r 2> /dev/null <<END_OF_INPUT; echo > /dev/null\n"
  577       . "\\($tex\\)\n"
  578       . "END_OF_INPUT\n";
  579 
  580 
  581     # call tth
  582     my $result = `$tthCommand`;
  583     if ($?) {
  584       return "<b>[tth failed: $? $@]</b>";
  585     }
  586     return $result;
  587   } elsif ($displayMode eq "images") {
  588     # how are we going to name this?
  589     my $targetPathCommon = "/png/"
  590       . $user->id . "."
  591       . $set->id . "."
  592       . $problem->id . "."
  593       . $answerResult->{ans_name} . ".png";
  594 
  595     # figure out where to put things
  596     my $wd = tempdir("webwork-dvipng-XXXXXXXX", DIR => $ce->{courseDirs}->{html_temp});
  597     my $latex = $ce->{externalPrograms}->{latex};
  598     my $dvipng = $ce->{externalPrograms}->{dvipng};
  599     my $targetPath = $ce->{courseDirs}->{html_temp} . $targetPathCommon;
  600         # should use surePathToTmpFile, but we have to
  601         # isolate it from the problem enivronment first
  602     my $targetURL = $ce->{courseURLs}->{html_temp} . $targetPathCommon;
  603 
  604     # call dvipng to generate a preview
  605     dvipng($wd, $latex, $dvipng, $tex, $targetPath);
  606     if (-e $targetPath) {
  607       return "<img src=\"$targetURL\" alt=\"$tex\" />";
  608     } else {
  609       return "<b>[math2img failed]</b>";
  610     }
  611   }
  612 }
  613 
  614 ##### permission queries #####
  615 
  616 # this stuff should be abstracted out into the permissions system
  617 # however, the permission system only knows about things in the
  618 # course environment and the username. hmmm...
  619 
  620 # also, i should fix these so that they have a consistent calling
  621 # format -- perhaps:
  622 #   canPERM($courseEnv, $user, $set, $problem, $permissionLevel)
  623 
  624 sub canShowCorrectAnswers($$) {
  625   my ($permissionLevel, $answerDate) = @_;
  626   return $permissionLevel > 0 || time > $answerDate;
  627 }
  628 
  629 sub canShowSolutions($$) {
  630   my ($permissionLevel, $answerDate) = @_;
  631   return canShowCorrectAnswers($permissionLevel, $answerDate);
  632 }
  633 
  634 sub canRecordAnswers($$$$$) {
  635   my ($permissionLevel, $openDate, $dueDate, $maxAttempts, $attempts) = @_;
  636   my $permHigh = $permissionLevel > 0;
  637   my $timeOK = time >= $openDate && time <= $dueDate;
  638   my $attemptsOK = $maxAttempts == -1 || $attempts <= $maxAttempts;
  639   my $recordAnswers = $permHigh || ($timeOK && $attemptsOK);
  640   return $recordAnswers;
  641 }
  642 
  643 sub mustRecordAnswers($) {
  644   my ($permissionLevel) = @_;
  645   return $permissionLevel == 0;
  646 }
  647 
  648 1;

aubreyja at gmail dot com
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