ExpressionScript Engine roadmap

This page is for tracking the development status and TODO lists for ExpressionManager

Status

1.92+ stable was released in March, 2012.

Upgrade Notes

There are a few backwards incompatibilities between 1.92 and 1.91.  Please read them carefully.

Wish List for EM-Related Enhancements

Near Term (relatively easy)

1. Add support for "this"
   1. Already lets you access this, this.NAOK, this.shown, etc. and show as valid within relevance equations
   2. Should provide access to all array values too - so create several:  this, this_nc (no comments), this_oc  (only comments)
   3. Should be expanded by EM during JavaScript generation to be comma separated values
   4. So, if you want to sum all values for an array, you'd say sum(this.NAOK) (or count(this.NAOK) to count number of answers)
   5. Macro expansion should occur in group.php as  cycles through each question
   6. Value should be forcibly cleared at start of each group/page otherwise use of this in a group description would have unpredictable results
2. Add aliases for common array processing values
   1. qcode_vars - acts like this, so can do sum(qcode_vars.NAOK), count(qcode_vars.NAOK), implode(', ', qcode_vars.shown), stddev(qcode_vars.NAOK), etc.
   2. qcode_vars_nc (no comments), qcode_vars_oc (only comments)
3. Add aliases needed to do row and column sums within arrays yet still properly handle array_filter
   1. qcode_rowname_vars
   2. qcode_colname_vars
4. Enhance EM'support for array_filter
   1. If the filter is completely dependent upon questions on prior pages, then irrelevant filtered values don't need to be generated in the HTML
   2. Currently, all array_filter items are generated, but appropriately hidden.  For large arrays, this can lead to a lot of never-to-be-used code

Longer Term (harder)

• #Enhance Expression Manager|Enhance Expression Manager
• #Optimize LimeSurvey for Long Surveys and better performance and maintenance in general|Optimize LimeSurvey for Long Surveys and better performance and maintenance in general

Performance Tuning Notes

ExpressionManager can be called dozens to hundreds of times per page.  Instead, it should be possible to concatenate together the roughly tailored parts of the survey page and call Expression Manager once per page (or at least fewer times).

To accomplish this, two things are needed:

1. Ensure that all replacement values are correct when  called.  Some values like {QUESTION} change multiple times per page.  Others are constant across all pages.
2. Find way to concatenate together all page components priort to calling ExpressionManager.

For values that change multiple times per page (like {QUESTION}), I'd like to replace calls to templatereplace(), replaceTokens(), insertAnsReplace(), dTexts, and replaceFields() (several of which call ExpressionManager) as follows:

• Templates: (except for Group and Question) - return as is so they get processed at the end
• Group Template:  Replace {GROUP} with something like {GROUP_N} which ExpressionManager would then substitute at the end
• Question Template:  Replace {QUESTION}  and {ANSWER} with something like {QUESTION_N} and {ANSWER_N} which would also get replaced after the whole page was composed.

When are each of the following attributes changed?

Here are the possibilities:

• global - means that the value is global for the LimeSurvey instance (across all surveys and sessions
• survey - means each survey might have a different value
• session - means the value should be static across a given session
• page - means that the value on each page might differ
• group - means might differ for each group
• questions - means might differ for each question
• answer - means  might differ for each answer option
• no processing needed - means EM should only do a plain replace on these, no processing of the contents

Attribute	When Changed
AID	answer
ANSWER	answer
ANSWERSCLEARED	survey
ASSESSMENTS	page
ASSESSMENT_CURRENT_TOTAL	page
ASSESSMENT_HEADING	survey
CHECKJAVASCRIPT	survey - no processing needed
CLEARALL	survey
CLOSEWINDOW	survey
COMPLETED	session
DATESTAMP	page - no processing needed
EXPIRY	survey - no processing needed
GID	group
GROUPDESCRIPTION	group
GROUPNAME	group
LANG	page
LANGUAGECHANGER	page
LOADERROR	survey
LOADFORM	survey
LOADHEADING	survey
LOADMESSAGE	survey
NAVIGATOR	page
NOSURVEYID	survey - no processing needed
NUMBEROFQUESTIONS	survey
PERCENTCOMPLETE	page
PRIVACY	survey
PRIVACYMESSAGE	survey
QID	question
QUESTION	question
QUESTIONHELP	question
QUESTIONHELPPLAINTEXT	question
QUESTION_CLASS	question
QUESTION_CODE	question
QUESTION_ESSENTIALS	question
QUESTION_FILE_VALID_MESSAGE	question
QUESTION_HELP	question
QUESTION_INPUT_ERROR_CLASS	question
QUESTION_MANDATORY	question
QUESTION_MAN_CLASS	question
QUESTION_MAN_MESSAGE	question
QUESTION_NUMBER	question
QUESTION_TEXT	question
QUESTION_VALID_MESSAGE	question
REGISTERERROR	survey
REGISTERFORM	survey
REGISTERMESSAGE1	survey
REGISTERMESSAGE2	survey
RESTART	survey
RETURNTOSURVEY	survey
SAVE	survey
SAVEALERT	survey
SAVEDID	survey
SAVEERROR	survey
SAVEFORM	survey
SAVEHEADING	survey
SAVEMESSAGE	survey
SGQ	question
SID	survey
SITENAME	global
SUBMITBUTTON	survey
SUBMITCOMPLETE	survey
SUBMITREVIEW	survey
SURVEYCONTACT	survey
SURVEYDESCRIPTION	survey
SURVEYFORMAT	survey
SURVEYLANGAGE	survey
SURVEYLIST	survey
SURVEYLISTHEADING	survey
SURVEYNAME	survey
TEMPLATECSS	survey
TEMPLATEURL	survey
THEREAREXQUESTIONS	suvey
TOKEN	session - no processing needed
URL	survey
WELCOME	survey

Where within LimeSurvey is each Keyword Used?

A green 1 means that the keyword is used in that file at least once.