--- trunk/webwork2/lib/WeBWorK/PG.pm 2002/07/11 23:27:10 425 +++ trunk/webwork2/lib/WeBWorK/PG.pm 2003/06/14 06:03:15 1169 @@ -1,43 +1,55 @@ +################################################################################ +# WeBWorK mod_perl (c) 2000-2002 WeBWorK Project +# $Id$ +################################################################################ + package WeBWorK::PG; -# hide PG::* from the not-yet-insane. +=head1 NAME + +WeBWorK::PG - Wrap the action of the PG Translator in an easy-to-use API. + +=cut use strict; use warnings; -use WeBWorK::Utils qw(readFile formatDateTime); -use WeBWorK::DB::Classlist; -use WeBWorK::DB::WW; +use File::Path qw(rmtree); +use WeBWorK::PG::ImageGenerator; use WeBWorK::PG::Translator; +use WeBWorK::Utils qw(readFile formatDateTime writeTimingLogEntry makeTempDirectory); sub new($$$$$$$$) { my $invocant = shift; my $class = ref($invocant) || $invocant; my ( $courseEnv, - $userName, + $user, $key, - $setName, - $problemNumber, + $set, + $problem, + $psvn, + $formFields, # in CGI::Vars format $translationOptions, # hashref containing options for the # translator, such as whether to show # hints and the display mode to use - $formFields, # in CGI::Vars format ) = @_; - # get database information - my $classlist = WeBWorK::DB::Classlist->new($courseEnv); - my $wwdb = WeBWorK::DB::WW->new($courseEnv); - my $user = $classlist->getUser($userName); - my $set = $wwdb->getSet($userName, $setName); - my $problem = $wwdb->getProblem($userName, $setName, $problemNumber); - my $psvn = $wwdb->getPSVN($userName, $setName); + # write timing log entry + writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", + "user=".$user->user_id.",problem=".$courseEnv->{courseName}."/".$set->set_id."/".$problem->problem_id.",mode=".$translationOptions->{displayMode}, + "begin"); + + # install a local warn handler to collect warnings + my $warnings = ""; + local $SIG{__WARN__} = sub { $warnings .= shift } + if $courseEnv->{pg}->{options}->{catchWarnings}; # create a Translator - warn "PG: creating a Translator\n"; + #warn "PG: creating a Translator\n"; my $translator = WeBWorK::PG::Translator->new; # set the directory hash - warn "PG: setting the directory hash\n"; + #warn "PG: setting the directory hash\n"; $translator->rh_directories({ courseScriptsDirectory => $courseEnv->{webworkDirs}->{macros}, macroDirectory => $courseEnv->{courseDirs}->{macros}, @@ -46,95 +58,159 @@ }); # evaluate modules and "extra packages" - warn "PG: evaluating modules and \"extra packages\"\n"; + #warn "PG: evaluating modules and \"extra packages\"\n"; my @modules = @{ $courseEnv->{pg}->{modules} }; - foreach my $module_packages (@modules) { - # the first item in $module_packages is the main package - $translator->evaluate_modules(shift @$module_packages); + foreach my $module_packages_ref (@modules) { + my ($module, @extra_packages) = @$module_packages_ref; + # the first item is the main package + $translator->evaluate_modules($module); # the remaining items are "extra" packages - $translator->load_extra_packages(@$module_packages); + $translator->load_extra_packages(@extra_packages); } # set the environment (from defineProblemEnvir) - warn "PG: setting the environment (from defineProblemEnvir)\n"; - $translator->environment(defineProblemEnvir( - $courseEnv, $user, $key, $set, $problem, $psvn, $formFields, $translationOptions)); + #warn "PG: setting the environment (from defineProblemEnvir)\n"; + my $envir = defineProblemEnvir( + $courseEnv, + $user, + $key, + $set, + $problem, + $psvn, + $formFields, + $translationOptions, + ); + $translator->environment($envir); # initialize the Translator - warn "PG: initializing the Translator\n"; + #warn "PG: initializing the Translator\n"; $translator->initialize(); - # load PG.pl and dangerousMacros.pl using unrestricted_load + # load IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load # i'd like to change this at some point to have the same sort of interface to global.conf # that the module loading does -- have a list of macros to load unrestrictedly. - warn "PG: loading PG.pl and dangerousMacros.pl using unrestricted_load\n"; - my $pg_pl = $courseEnv->{webworkDirs}->{macros} . "/PG.pl"; - my $dangerousMacros_pl = $courseEnv->{webworkDirs}->{macros} . "/dangerousMacros.pl"; - my $err = $translator->unrestricted_load($pg_pl); - warn "Error while loading $pg_pl: $err" if $err; - $err = $translator->unrestricted_load($dangerousMacros_pl); - warn "Error while loading $dangerousMacros_pl: $err" if $err; + #warn "PG: loading IO.pl, PG.pl, and dangerousMacros.pl using unrestricted_load\n"; + foreach (qw(IO.pl PG.pl dangerousMacros.pl)) { + my $macroPath = $courseEnv->{webworkDirs}->{macros} . "/$_"; + my $err = $translator->unrestricted_load($macroPath); + warn "Error while loading $macroPath: $err" if $err; + } # set the opcode mask (using default values) - warn "PG: setting the opcode mask (using default values)\n"; + #warn "PG: setting the opcode mask (using default values)\n"; $translator->set_mask(); # store the problem source - warn "PG: storing the problem source\n"; - my $sourceFile = $courseEnv->{courseDirs}->{templates}."/".$problem->source_file; - $translator->source_string(readFile($sourceFile)); + #warn "PG: storing the problem source\n"; + my $sourceFile = ( defined($translationOptions->{override_problem_source}) ) ? + $translationOptions->{override_problem_source} : + $problem->source_file; + $sourceFile = $courseEnv->{courseDirs}->{templates}."/".$sourceFile + unless ($sourceFile =~ /^\//); + eval { $translator->source_string(readFile($sourceFile)) }; + if ($@) { + # well, we couldn't get the problem source, for some reason. + return bless { + translator => $translator, + head_text => "", + body_text => < {}, + result => {}, + state => {}, + errors => "Failed to read the problem source file.", + warnings => $warnings, + flags => {error_flag => 1}, + }, $class; + } # install a safety filter (&safetyFilter) - warn "PG: installing a safety filter\n"; + #warn "PG: installing a safety filter\n"; $translator->rf_safety_filter(\&safetyFilter); + # write timing log entry -- the translator is now all set up + writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", + "initialized", + "intermediate"); + # translate the PG source into text - warn "PG: translating the PG source into text\n"; + #warn "PG: translating the PG source into text\n"; $translator->translate(); - # [in Problem.pm and processProblem8.pl, "install a grader" is here] + # after we're done translating, we may have to clean up after the + # translator: - # process student answers - warn "PG: processing student answers\n"; - $translator->process_answers($formFields); - - # retrieve the problem state and give it to the translator - warn "PG: retrieving the problem state and giving it to the translator\n"; - $translator->rh_problem_state({ - recorded_score => $problem->status, - num_of_correct_ans => $problem->num_correct, - num_of_incorrect_ans => $problem->num_incorrect, - }); + # for example, HTML_img mode uses a tempdir for dvipng's temp files.\ + # We have to remove it. + if ($envir->{dvipngTempDir}) { + rmtree($envir->{dvipngTempDir}, 0, 0); + } - # determine an entry order -- the ANSWER_ENTRY_ORDER flag is built by - # the PG macro package (PG.pl) - warn "PG: determining an entry order\n"; - my @answerOrder = - $translator->rh_flags->{ANSWER_ENTRY_ORDER} - ? @{ $translator->rh_flags->{ANSWER_ENTRY_ORDER} } - : keys %{ $translator->rh_evaluated_answers }; - - # install a grader -- use the one specified in the problem, - # or fall back on the default from the course environment. - # (two magic strings are accepted, to avoid having to - # reference code when it would be difficult.) - warn "PG: installing a grader\n"; - my $grader = $translator->rh_flags->{PROBLEM_GRADER_TO_USE} - || $courseEnv->{pg}->{options}->{grader}; - $grader = $translator->rf_std_problem_grader - if $grader eq "std_problem_grader"; - $grader = $translator->rf_avg_problem_grader - if $grader eq "avg_problem_grader"; - die "Problem grader $grader is not a CODE reference." - unless ref $grader eq "CODE"; - $translator->rf_problem_grader($grader); - - # grading the problem - warn "PG: grade the problem\n"; - my ($result, $state) = $translator->grade_problem( - answers_submitted => $translationOptions->{processAnswers}, - ANSWER_ENTRY_ORDER => \@answerOrder, - ); + # HTML_dpng, on the other hand, uses an ImageGenerator. We have to + # render the queued equations. + if ($envir->{imagegen}) { + my $sourceFile = $courseEnv->{courseDirs}->{templates} . "/" . $problem->source_file; + my %mtimeOption = -e $sourceFile + ? (mtime => (stat $sourceFile)[9]) + : (); + + $envir->{imagegen}->render( + refresh => $translationOptions->{refreshMath2img}, + %mtimeOption, + ); + } + + my ($result, $state); # we'll need these on the other side of the if block! + if ($translationOptions->{processAnswers}) { + + # process student answers + #warn "PG: processing student answers\n"; + $translator->process_answers($formFields); + + # retrieve the problem state and give it to the translator + #warn "PG: retrieving the problem state and giving it to the translator\n"; + $translator->rh_problem_state({ + recorded_score => $problem->status, + num_of_correct_ans => $problem->num_correct, + num_of_incorrect_ans => $problem->num_incorrect, + }); + + # determine an entry order -- the ANSWER_ENTRY_ORDER flag is built by + # the PG macro package (PG.pl) + #warn "PG: determining an entry order\n"; + my @answerOrder = + $translator->rh_flags->{ANSWER_ENTRY_ORDER} + ? @{ $translator->rh_flags->{ANSWER_ENTRY_ORDER} } + : keys %{ $translator->rh_evaluated_answers }; + + # install a grader -- use the one specified in the problem, + # or fall back on the default from the course environment. + # (two magic strings are accepted, to avoid having to + # reference code when it would be difficult.) + #warn "PG: installing a grader\n"; + my $grader = $translator->rh_flags->{PROBLEM_GRADER_TO_USE} + || $courseEnv->{pg}->{options}->{grader}; + $grader = $translator->rf_std_problem_grader + if $grader eq "std_problem_grader"; + $grader = $translator->rf_avg_problem_grader + if $grader eq "avg_problem_grader"; + die "Problem grader $grader is not a CODE reference." + unless ref $grader eq "CODE"; + $translator->rf_problem_grader($grader); + + # grade the problem + #warn "PG: grading the problem\n"; + ($result, $state) = $translator->grade_problem( + answers_submitted => $translationOptions->{processAnswers}, + ANSWER_ENTRY_ORDER => \@answerOrder, + ); + + } + + # write timing log entry + writeTimingLogEntry($courseEnv, "WeBWorK::PG::new", "", "end"); # return an object which contains the translator and the results of # the translation process. this is DIFFERENT from the "format expected @@ -146,8 +222,8 @@ answers => $translator->rh_evaluated_answers, result => $result, state => $state, - errors => $translator->errors, # *** what is this doing? - warnings => undef, # *** gotta catch warnings eventually... + errors => $translator->errors, + warnings => $warnings, flags => $translator->rh_flags, }, $class; } @@ -168,37 +244,43 @@ my %envir; + # ---------------------------------------------------------------------- + # PG environment variables # from docs/pglanguage/pgreference/environmentvariables as of 06/25/2002 # any changes are noted by "ADDED:" or "REMOVED:" # Vital state information - # ADDED: displayHintsQ, displaySolutionsQ, externalTTHPath + # ADDED: displayHintsQ, displaySolutionsQ, refreshMath2img, + # texDisposition $envir{psvn} = $psvn; $envir{psvnNumber} = $envir{psvn}; - $envir{probNum} = $problem->id; + $envir{probNum} = $problem->problem_id; $envir{questionNumber} = $envir{probNum}; $envir{fileName} = $problem->source_file; $envir{probFileName} = $envir{fileName}; - $envir{problemSeed} = $problem->problem_seed; + $envir{problemSeed} = (defined($options->{override_seed}) ) ? $options->{override_seed} :$problem->problem_seed; $envir{displayMode} = translateDisplayModeNames($options->{displayMode}); $envir{languageMode} = $envir{displayMode}; $envir{outputMode} = $envir{displayMode}; - $envir{displayHintsQ} = $options->{hints}; - $envir{displaySolutionsQ} = $options->{solutions}; - $envir{externalTTHPath} = $courseEnv->{externalPrograms}->{tth}; + $envir{displayHintsQ} = $options->{showHints}; + $envir{displaySolutionsQ} = $options->{showSolutions}; + # FIXME: this is HTML_img specific + #$envir{refreshMath2img} = $options->{refreshMath2img}; + $envir{texDisposition} = "pdf"; # in webwork-modperl, we use pdflatex # Problem Information - # ADDED: courseName + # ADDED: courseName, formatedDueDate $envir{openDate} = $set->open_date; $envir{formattedOpenDate} = formatDateTime($envir{openDate}); $envir{dueDate} = $set->due_date; $envir{formattedDueDate} = formatDateTime($envir{dueDate}); + $envir{formatedDueDate} = $envir{formattedDueDate}; # typo in many header files $envir{answerDate} = $set->answer_date; $envir{formattedAnswerDate} = formatDateTime($envir{answerDate}); - $envir{numOfAttempts} = $problem->num_correct + $problem->num_incorrect; + $envir{numOfAttempts} = ($problem->num_correct || 0) + ($problem->num_incorrect || 0); $envir{problemValue} = $problem->value; $envir{sessionKey} = $key; $envir{courseName} = $courseEnv->{courseName}; @@ -210,40 +292,84 @@ $envir{sectionNumber} = $envir{sectionName}; $envir{recitationName} = $user->recitation; $envir{recitationNumber} = $envir{recitationName}; - $envir{setNumber} = $set->id; - $envir{studentLogin} = $user->id; + $envir{setNumber} = $set->set_id; + $envir{studentLogin} = $user->user_id; $envir{studentName} = $user->first_name . " " . $user->last_name; $envir{studentID} = $user->student_id; # Answer Information - # REMOVED: refSubmittedAnswers (alledgedly unused, causes errors) + # REMOVED: refSubmittedAnswers - $envir{inputs_ref} = $formFields; + $envir{inputs_ref} = $formFields; - # Default values for evaluating answers - - my $ansEvalDefaults = $courseEnv->{pg}->{ansEvalDefaults}; - $envir{$_} = $ansEvalDefaults->{$_} foreach (keys %$ansEvalDefaults); + # External Programs + # ADDED: externalLaTeXPath, externalDvipngPath, + # externalGif2EpsPath, externalPng2EpsPath + + $envir{externalTTHPath} = $courseEnv->{externalPrograms}->{tth}; + $envir{externalLaTeXPath} = $courseEnv->{externalPrograms}->{latex}; + $envir{externalDvipngPath} = $courseEnv->{externalPrograms}->{dvipng}; + $envir{externalGif2EpsPath} = $courseEnv->{externalPrograms}->{gif2eps}; + $envir{externalPng2EpsPath} = $courseEnv->{externalPrograms}->{png2eps}; + $envir{externalGif2PngPath} = $courseEnv->{externalPrograms}->{gif2png}; # Directories and URLs # REMOVED: courseName + # ADDED: dvipngTempDir $envir{cgiDirectory} = undef; $envir{cgiURL} = undef; $envir{classDirectory} = undef; $envir{courseScriptsDirectory} = $courseEnv->{webworkDirs}->{macros}."/"; $envir{htmlDirectory} = $courseEnv->{courseDirs}->{html}."/"; - $envir{htmlURL} = $courseEnv->{courseURLs}->{html}; + $envir{htmlURL} = $courseEnv->{courseURLs}->{html}."/"; $envir{macroDirectory} = $courseEnv->{courseDirs}->{macros}."/"; $envir{templateDirectory} = $courseEnv->{courseDirs}->{templates}."/"; $envir{tempDirectory} = $courseEnv->{courseDirs}->{html_temp}."/"; - $envir{tempURL} = $courseEnv->{courseURLs}->{html_temp}; + $envir{tempURL} = $courseEnv->{courseURLs}->{html_temp}."/"; $envir{scriptDirectory} = undef; - $envir{webworkDocsURL} = $courseEnv->{webworkURLs}->{docs}; + $envir{webworkDocsURL} = $courseEnv->{webworkURLs}->{docs}."/"; + # FIXME: this is HTML_img mode-specific + #$envir{dvipngTempDir} = $options->{displayMode} eq 'images' + # ? makeTempDirectory($envir{tempDirectory}, "webwork-dvipng") + # : undef; + + # Information for sending mail + + $envir{mailSmtpServer} = $courseEnv->{mail}->{smtpServer}; + $envir{mailSmtpSender} = $courseEnv->{mail}->{smtpSender}; + $envir{ALLOW_MAIL_TO} = $courseEnv->{mail}->{allowedRecipients}; - # Other things... (where's your brain?!?!) + # Default values for evaluating answers - $envir{PROBLEM_GRADER_TO_USE} = $courseEnv->{pg}->{options}->{grader}; + my $ansEvalDefaults = $courseEnv->{pg}->{ansEvalDefaults}; + $envir{$_} = $ansEvalDefaults->{$_} foreach (keys %$ansEvalDefaults); + + # ---------------------------------------------------------------------- + + my $basename = "equation-$envir{psvn}.$envir{probNum}"; + $basename .= ".$envir{problemSeed}" if $envir{problemSeed}; + + # Object for generating equation images + $envir{imagegen} = WeBWorK::PG::ImageGenerator->new( + tempDir => $courseEnv->{webworkDirs}->{tmp}, # global temp dir + dir => $envir{tempDirectory}, + url => $envir{tempURL}, + basename => $basename, + latex => $envir{externalLaTeXPath}, + dvipng => $envir{externalDvipngPath}, + ); + + # Other things... + $envir{QUIZ_PREFIX} = $options->{QUIZ_PREFIX}; # used by quizzes + $envir{PROBLEM_GRADER_TO_USE} = $courseEnv->{pg}->{options}->{grader}; + $envir{PRINT_FILE_NAMES_FOR} = $courseEnv->{pg}->{specialPGEnvironmentVars}->{PRINT_FILE_NAMES_FOR}; + + # variables for interpreting capa problems. + $envir{CAPA_Tools} = $courseEnv->{pg}->{specialPGEnvironmentVars}->{CAPA_Tools}; + $envir{CAPA_MCTools} = $courseEnv->{pg}->{specialPGEnvironmentVars}->{CAPA_MCTools}; + $envir{CAPA_Graphics_URL} = $courseEnv->{pg}->{specialPGEnvironmentVars}->{CAPA_Graphics_URL}; + $envir{CAPA_GraphicsDirectory} = $courseEnv->{pg}->{specialPGEnvironmentVars}->{CAPA_GraphicsDirectory}; return \%envir; } @@ -251,9 +377,10 @@ sub translateDisplayModeNames($) { my $name = shift; return { + tex => "TeX", plainText => "HTML", formattedText => "HTML_tth", - images => "Latex2HTML" + images => "HTML_dpng", # "HTML_img", }->{$name}; } @@ -271,8 +398,8 @@ } # replace ^ with ** (for exponentiation) # $answer =~ s/\^/**/g; - # Return if forbidden characters are found - unless ($answer =~ /^[a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)]+$/ ) { + # Return if forbidden characters are found + unless ($answer =~ /^[a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\[\]\(\)\,\|]+$/ ) { $answer =~ tr/a-zA-Z0-9_\-\+ \t\/@%\*\.\n^\(\)/#/c; $errorno = "
There are forbidden characters in your answer: $submittedAnswer
"; return ($answer,$errorno); @@ -282,3 +409,256 @@ } 1; + +__END__ + +=head1 SYNOPSIS + + $pg = WeBWorK::PG->new( + $courseEnv, # a WeBWorK::CourseEnvironment object + $user, # a WeBWorK::DB::Record::User object + $sessionKey, + $set, # a WeBWorK::DB::Record::UserSet object + $problem, # a WeBWorK::DB::Record::UserProblem object + $psvn, + $formFields # in &WeBWorK::Form::Vars format + { # translation options + displayMode => "images", # (plainText|formattedText|images) + showHints => 1, # (0|1) + showSolutions => 0, # (0|1) + refreshMath2img => 0, # (0|1) + processAnswers => 1, # (0|1) + }, + ); + + $translator = $pg->{translator}; # WeBWorK::PG::Translator + $body = $pg->{body_text}; # text string + $header = $pg->{head_text}; # text string + $answerHash = $pg->{answers}; # WeBWorK::PG::AnswerHash + $result = $pg->{result}; # hash reference + $state = $pg->{state}; # hash reference + $errors = $pg->{errors}; # text string + $warnings = $pg->{warnings}; # text string + $flags = $pg->{flags}; # hash reference + +=head1 DESCRIPTION + +WeBWorK::PG encapsulates the PG translation process, making multiple calls to +WeBWorK::PG::Translator. Much of the flexibility of the Translator is hidden, +instead making choices that are appropriate for the webwork-modperl system. + +=head1 CONSTRUCTION + +=over + +=item new (ENVIRONMENT, USER, KEY, SET, PROBLEM, PSVN, FIELDS, OPTIONS) + +The C method creates a translator, initializes it using the parameters +specified, translates a PG file, and processes answers. It returns a reference +to a blessed hash containing the results of the translation process. + +=back + +=head2 Parameters + +=over + +=item ENVIRONMENT + +a WeBWorK::CourseEnvironment object + +=item USER + +a WeBWorK::User object + +=item KEY + +the session key of the current session + +=item SET + +a WeBWorK::Set object + +=item PROBLEM + +a WeBWorK::DB::Record::UserProblem object. The contents of the source_file +field can specify a PG file either by absolute path or path relative to the +"templates" directory. I + +=item PSVN + +the problem set version number + +=item FIELDS + +a reference to a hash (as returned by &WeBWorK::Form::Vars) containing form +fields submitted by a problem processor. The translator will look for fields +like "AnSwEr[0-9]" containing submitted student answers. + +=item OPTIONS + +a reference to a hash containing the following data: + +=over + +=item displayMode + +one of "plainText", "formattedText", or "images" + +=item showHints + +boolean, render hints + +=item showSolutions + +boolean, render solutions + +=item refreshMath2img + +boolean, force images created by math2img (in "images" mode) to be recreated, +even if the PG source has not been updated. FIXME: change the name of this +option to "refreshEquations" and update the docs accordingly. + +=item processAnswers + +boolean, call answer evaluators and graders + +=back + +=back + +=head2 RETURN VALUE + +The C method returns a blessed hash reference containing the following +fields. More information can be found in the documentation for +WeBWorK::PG::Translator. + +=over + +=item translator + +The WeBWorK::PG::Translator object used to render the problem. + +=item head_text + +HTML code for the EheadE block of an resulting web page. Used for +JavaScript features. + +=item body_text + +HTML code for the EbodyE block of an resulting web page. + +=item answers + +An C object containing submitted answers, and results of answer +evaluation. + +=item result + +A hash containing the results of grading the problem. + +=item state + +A hash containing the new problem state. + +=item errors + +A string containing any errors encountered while rendering the problem. + +=item warnings + +A string containing any warnings encountered while rendering the problem. + +=item flags + +A hash containing PG_flags (see the Translator docs). + +=back + +=head1 OPERATION + +WeBWorK::PG goes through the following operations when constructed: + +=over + +=item Get database information + +Retrieve information about the current user, set, and problem from the +database. + +=item Create a translator + +Instantiate a WeBWorK::PG::Translator object. + +=item Set the directory hash + +Set the translator's directory hash (courseScripts, macros, templates, and temp +directories) from the course environment. + +=item Evaluate PG modules + +Using the module list from the course environment (pg->modules), perform a +"use"-like operation to evaluate modules at runtime. + +=item Set the problem environment + +Use data from the user, set, and problem, as well as the course environemnt and +translation options, to set the problem environment. + +=item Initialize the translator + +Call &WeBWorK::PG::Translator::initialize. What more do you want? + +=item Load PG.pl and dangerousMacros.pl + +These macros must be loaded without opcode masking, so they are loaded here. + +=item Set the opcode mask + +Set the opcode mask to the default specified by WeBWorK::PG::Translator. + +=item Load the problem source + +Give the problem source to the translator. + +=item Install a safety filter + +The safety filter is used to preprocess student input before evaluation. The +default safety filter, &WeBWorK::PG::safetyFilter, is used. + +=item Translate the problem source + +Call &WeBWorK::PG::Translator::translate to render the problem source into the +format given by the display mode. + +=item Process student answers + +Use form field inputs to evaluate student answers. + +=item Load the problem state + +Use values from the database to initialize the problem state, so that the +grader will have a point of reference. + +=item Determine an entry order + +Use the ANSWER_ENTRY_ORDER flag to determine the order of answers in the +problem. This is important for problems with dependancies among parts. + +=item Install a grader + +Use the PROBLEM_GRADER_TO_USE flag, or a default from the course environment, +to install a grader. + +=item Grade the problem + +Use the selected grader to grade the problem. + +=back + +=head1 AUTHOR + +Written by Sam Hathaway, sh002i (at) math.rochester.edu. + +=cut