Why not open it up via a include file which can be edited via settings.
I would like to see a easy way to get more php functions exposed to EM.
The LOC needed to expose a new php function into EM seem to be not that huge.

You already proposed the plugin idea over two years ago.
https://www.limesurvey.org/forum/development/100938-extending-em_core_helper-php

To me ExpressionManager seems to be a big blackhole which nobody likes to really touch.
Rock–paper–scissors might help finding the right developer to refactor it ;-)
The very old wishlist is still here:
https://manual.limesurvey.org/Project_Ideas_for_GSoC_2012#Enhance_Expression_Manager

You are right, did this already (2Y7M ago), forgot it meanwhile :o

Anyhow it is not that hard to write new functions for the EM and some features requested in the wishlist you mentioned are avaliable meanwhile.

My idea to realize an EM extender like a plugin is based on the possibility to share plugins with the community.

Unfortunately plugins and plugin how-to's are
a) not very well documented at the moment and
b) the interface on the website to share them seems to be a little abandoned - at least compared to e.g. the R community ( https://cran.r-project.org/ > see Packages) or some CMS I'm working with.

Although this would be a real booster for LS!

Expression Manager NEED to be extendable :).

1. New EM->knowVars (and way to set it)
2. New function
3. Add specific Expression (like currently ranking default/min value etc …)

:)

It's a +1000 for this Feature

Finally found a way to implement this!

Working with php and js, so usable in question.by-question, group-by-group and all-in-one mode of showing a survey.
See http://www.sdi-research.co.at/dev/iSurvey300/index.php/548491?newtest=Y&lang=en for a running example

created pull requests for em_core_helper.php (~30 lines of code), and sample extensions files (php, js)
https://github.com/LimeSurvey/LimeSurvey/pull/1077/commits/941b655accb2e7e05109da98830fb36d240edb85
https://github.com/LimeSurvey/LimeSurvey/pull/1077/commits/c03aa8de82b142388ae65d5cd6b73b938458953f
https://github.com/LimeSurvey/LimeSurvey/pull/1077/commits/a0c0f8b1198bf99e55f44fc6d4887dd0671be2e1

Yep : EM function a php function (existing or not) + a js function (existing or not).

But , i think we need to move all of this to an helper or model to more easily managed after, and maybe add some caching (because test/read file is time consuming).

I think @olle like if we have "one function => one directory", and maybe he a 'config' … file

Personnaly, i had it with event if i do it. But think LS GMBH don't like event.

@orvil : you don't have limesurvey-team irc access ?

@DenisChenu: as someone wrote once the LEM is genius, but a big black hole, hard to understand and to maintain.
So on the long run I agree: the functionality should be moved modular into the MVC concept (as eg. questions too ;) But: why not combine this step with migration to yii2 ?

Think this will take quite some time (1-2 years probably?). So the proposed solution is an interim way, but I think all created additional functions can be migrated to a new solution then easily.

By the way: the folders and folder structure i choose for implementation is a suggestion => an other structure and folder naming is possible too, to pre-fit a modular concept

Finally, no, I'm sorry I don't have a limesurvey-team irc access.

Can this be done easily with a new event?

@olle : it's what i think adding a new event, plugin can add function to EM

@DenisChenu: Hi, do you have some some progress with the em extension/plugin already?
If not, i will have some time this weekend to dig into (hopefilly) Or maybe there is a way to develop this together?
Found some questions in the forum with typical need of an EM solution (e.g. how to generate a list of non repeating random variables)

OK, well, if anyone makes a PR we can merge it.

As you suggested the em plugin requires three++ steps to take:

1. to add an event handler into the em helper file
2. to create a pattern for 2 files with additional php / js functions
3. the plugin
   ...
   testing, cursing, testing again, cursing again,... ;)

@olle: sorry I'm a noop: what's meant by PR?

PR = pull request (on github).

oh, that easy :)))

https://github.com/LimeSurvey/LimeSurvey/pull/1081

I have some issue with travis, i think it's because i made the pull request on a old version.

I redo it , but same principle done

Develop Travis is broken right now. Master should work.

No, i have an issue on my commit, i fix it today :)

Fix committed to master_13513 branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=28297

Fix committed to develop branch: http://bugs.limesurvey.org/plugin.php?page=Source/view&id=28345