Generico is a simple templating filter, that allows you to set up text and code snippet templates for use in Moodle text areas. It allows an unlimited number of templates to be registered. When Moodle encounters a Generico filter string it will use the data in the filter string to fill out the template, and insert it into the page. 

It is useful for ad-hoc template purposes where writing a new plugin would be overkill, or just for re-using common pieces of text. It can be used to centralise and manage the embedding of iframe content from video hosting services, and educational app providers.

In the latest version there are approx. 20 presets from which you can make templates. They include templates for an info box, tabset, accordian, lightbox and image gallery. And there is a companion Atto editor plugin for Generico. The combination of these two features make it possible to use Generico like the Wordpress shortcode plugins.

This 8 minute video walks through the basic Generico Filter and should give you a good idea of what it is, and how it works. 

How it works

Templates for use with the filter are available at:

Site Administration -> plugins -> filters -> Generico -> templates

A template primarily consists of a "key", a "template," and some "defaults." (It can also load CSS and Javascript. But for now lets keep things simple.)

The key is just a one word name, that tells Generico which template to use. 

The template is just passage of text that you want to use, and the parts of the template that you want to mark as variables you surround in @@ marks.

The defaults are a comma delimited list of variablename=value pairs. It is possible to specify multiple values for a single variable in the defaults. The Generico Atto editor plugin will display these values in a drop down list. eg size="100|120|140".  The first of the values will be the true "default."

Here is an example template.

templatekey: wildthings

template: Inside this box are @@thing1@@ and @@thing2@@

template defaults: thing2=Silly

A possible filter string for this "wildthings" template would look like this:

{GENERICO:type=wildthings,thing1=Sally}

Generico would replace the above filter string with:

"Inside this box are Sally and Silly"

The filter string must follow this format,

{GENERICO:type=templatekey,variable1=data1,variable2=data2}

The wildthings example above is trivial of course. Instead imagine using it to embed YouTube videos by registering the standard iframe code YouTube gives you, as a template. Then it would only be necessary to insert the id of the video in a generico filter string and the template would do the rest. e.g

{GENERICO:type=youtube,id=ABC12345678}

USING PRESETS

Generico comes with about 20 template presets. By default they are not set up as templates yet. To create the actual template:

1. Open an empty template settings page
2. Select a preset from the dropdown list at the top of the page
   This will fill in the fields on the template settings page.
3. Press the "Save Changes" button at the bottom of the page.

USING BUNDLES

So that people can share the templates they have made, there is a system to share them called "bundles." On each template settings page there is a green bundle box.

If you click on the box, it will automatically download the "bundle" as a text file. If you then drag that bundle (or somebody else's bundle) onto the green bundle box of another template, it will fill the fields on that template settings page. Be sure to save the template after you have done that.

There are a number of bundles that people have shared over in the this forum thread. 
https://moodle.org/mod/forum/discuss.php?d=324771

And there is a special category here on the Moodle plugins directory for sharing templates: 
https://moodle.org/plugins/browse.php?list=category&id=69

USER PROFILE VARIABLES

It is also possible to add user profile variables to your templates. Just make the first part of the variable name USER: and the next part the name of the user profile field. It also works with custom profile fields. There are two "special" user profile fields, picurl and pic that respectively output the url of the user's profile pic, and their picture itself.

e.g

User's ice cream preference (custom profile field): @@USER:icecreampref@@
Users profile pic url: @@USER:picurl@@

User's profile pic:  @@USER:pic@@

INSTALLATION

Generico installs like any Moodle plugin. Please see here for more information on that process:
https://docs.moodle.org/en/Installing_plugins#Installing_directly_from_the_Moodle_plugins_directory

On the final page of the installation you will be able to register templates. its best to skip that step, and just press "save changes." Later you can do this from the Generico template settings pages.

After installing you will need to enable the Generico filter. You can enable the Generico filter at:

Site Administration -> plugins -> filters -> manage filters

More Documentation

https://docs.moodle.org/31/en/filter_generico

https://poodll.freshdesk.com/solution/articles/19000083258-how-do-widgets-work-for-developers-