Modify or extend default settings for a project - sublimetext3

Question

In a sublimetext3 project, is there a way to modify or extend, not replace, default settings?
To be specific, in a project I specify the paths of the folders to include in the project. Each folder has files and directories unique to that folder that I want to exclude using either folder_exclude_patterns or file_exclude_patterns; see documentation for Projects.
But as I understand this, these project settings replace not extend the default settings. What I would like, however, is to have a project setting that appends to the default pattern rather than replacing it. Is this possible?
Pseudo code that expresses what I would like to do:
"folders":
[
{
"path": "c:\\dir1",
"folder_exclude_patterns": default_folder_exclude_patterns + ["junk"]
},
{
"path": "C:\\dir2"
"folder_exclude_patterns": default_folder_exclude_patterns + ["old"]
},
]
If this is not possible, then I believe the only thing I can easily do is copy the default settings and replicate them for each folder item. Since I have multiple projects/folders and need to do this for file exclude, folder exclude and binary file settings, this will get tedious and be hard to maintain. Of course, this seems like it is ripe for a plugin, but that is not in the scope of what I am looking to do. (Of course if someone else has a plugin that does something like this, I would be happy to try it out! :-))

Answer 1

Unfortunately, due to the way Sublime is set up, higher-precedence settings replace lower-precedence ones, not supplement them. This is a good thing because many settings are either/or - what would you do if your user settings had "highlight_line": false while a project had "highlight_line": true, for example?
A plugin should be able to do the trick. sublime.Window contains the project_data() and set_project_data() methods, which allow you to retrieve and write project settings, respectively. You could add a "more_folder_exclude_patterns" key to each folder in your project with the additional patterns you would like to add to the defaults set in your Preferences.sublime-settings file. The plugin could then check if the "more" key exists, read both arrays, concatenate them, and write the result back to the .sublime-project file, erasing the "more" key at the same time. Finally, you could set up an event listener to run the plugin whenever you wanted - on save, upon loading a new file, etc.
EDIT
Here's a working example:
import sublime
import sublime_plugin
from copy import deepcopy
class ModifyExcludedFoldersCommand(sublime_plugin.WindowCommand):
def run(self):
proj_data = self.window.project_data() # dict
orig_proj_data = deepcopy(proj_data) # for comparison later
settings = sublime.load_settings("Preferences.sublime-settings")
fep = settings.get("folder_exclude_patterns") # list
for folder in proj_data["folders"]:
try:
if folder["folder_exclude_patterns"]:
break # if f_e_p is already present, our work is done
except KeyError:
pass # if it doesn't exist, move on to mfep
try:
mfep = folder["more_folder_exclude_patterns"]
new_fep = sorted(list(set(fep + mfep))) # combine f_e_p from
# Preferences and project,
# excluding duplicates using
# a set.
folder["folder_exclude_patterns"] = new_fep
del folder["more_folder_exclude_patterns"]
except KeyError:
pass # if mfep doesn't exist, just move on to the next folder
if proj_data != orig_proj_data:
self.window.set_project_data(proj_data)
class UpdateProjectData(sublime_plugin.EventListener):
def on_activated(self, view):
window = view.window()
window.run_command("modify_excluded_folders")
Save the file as Packages/User/modify_excluded_folders.py (where Packages is the folder opened when selecting Preferences -> Browse Packages...) and it should go into effect immediately. It will run each time a view is activated. It checks for the presence of a "folder_exclude_patterns" array in each folder defined in the current .sublime-project file, and if found it assumes everything is OK and passes on to the next folder. If that array is not found, it then checks for the presence of a "more_folder_exclude_patterns" array. If found, it does its magic and merges the contents with the existing "folder_exclude_patterns" array from your preferences (Default or User). It then writes a new "folder_exclude_patterns" array into the folder and deletes the "more_folder_exclude_patterns" array. Finally, it checks to see if any changes were made, and if so it writes the new data back to the .sublime-project file.