Leaflet_Views module refactored with D8 Dependency Injection (better coding practice & standards)

@szeidler that error you mention (regarding the plugin name change) is a proper matter of D8 configuration settings. It arises from the original views configuration yaml files, that will keep looking for the (original) "leafet_map" views plugin style.

To fix them you will need to export/copy (admin/config/development/configuration/single/export) each views config yaml file and re-import it (admin/config/development/configuration/full/import), with the following lines corrected:

............ (omissis)
      style:
        type: leaflet_map
............ (omissis)

new update patch on this rerolled on the current head. This should be tested. Hope will be reviewed in time not to make this old again ;-)

@pvhee tnx for your comments and suggestions.

Here is the updated patch for with you suggested more concise code.

Couple of things:
- I don't get your first note at the #8 comment: You seem to revert some of the work that went into #273657: No events are shown in year view or calendar month block (you changed number fields back to textfields).
It seems to be a 2008 D5 issue, regarding the Calendar module. Isn't it?
- right, we might need to provide an upgrade path in order to avoid the error regarding 'The "leafet_map" plugin does not exist.'. But how?
Might be just a copy class of the leaflet_views/src/Plugin/views/style/LeafletMap.php one, just with an annotation like the following ... ?

* @ViewsStyle(
* id = "leafet_map",
* title = @Translation("Leaflet map (uncorrect one)"),
* help = @Translation("Displays a View as a Leaflet map with a buggy id. Should be changed to the Leaflet map (classic) one ."),
* display_types = {"normal"},
* theme = "leaflet-map"
* )

@pvhee ok I fixed it (everything):

- re- included the code for the issue #2736573: Number validation in formatter forms not working, plus some further minor fixer on code refactoring and Drupal Standards
- I provided a (so called) upgrade path (that might be thought as temporary, but perfectly working, imho) in the form of a further LeafetMap Class View Style Plugin (id= leafet_map) that just extends the correct LaefletMap Class (id=leaflet_map), with any additional code (it works exactly as the id=leaflet_map one). In this way every user set with the (UN-CORRECT) leafet_map plugin id won't have any application error but just an advised message in the view backend that invites him to shift to the new correct and ANALOG Leaflet map (classic) one.

Hope this finally helps. Feel free to amend all this the way you prefer, and commit this to the head ...

A further improvement and a better "upgrade path" might be

1. - to extend the hook_requirements (the existing one should be moved in the .install file instead ...) that:
   • - check if there is an existing view (throughout the configuration management check via config.factory service) that uses the (bad) leafet_map id view display style;
   • - print a message to the user to invite him to run an application update (drush updb / update.php) to fix a bad leaflet views plugin id use.
2. add an hook_update (in the same .install file) that runs a views configuration change that moves every leafet_map id view display style to the correct one (leaflet_map), for the affected leaflet views.

Let me know if this upgrade path might be worth to be done (I just started to draft the hook_requirements update ...)

Ok, sure ... I will update this patch on this, by the we ;-) (and open a new issue on the leafet->leaflet change)

Here is a new rerolled patch, specifically regarding refactoring with dependency injections (more complaints with Drupal best practices and testability),
and skipping the matter regarding the error on the leafet_map view style plugin.

Once committed this to the head/actual dev of the project, I will open a new issue addressing a proper path to correct the leafet_map -> leaflet_map plugin name.
Just let us know when this will be committed/merged.