Make MusicMusterSignals a singleton class

Moved into datastructures.py

app/datastructures.py

@@ -0,0 +1,20 @@
+from PyQt6.QtCore import pyqtSignal, QObject
+
+from helpers import singleton
+
+
+@singleton
+class MusicMusterSignals(QObject):
+    """
+    Class for all MusicMuster signals. See:
+     - https://zetcode.com/gui/pyqt5/eventssignals/
+     - https://stackoverflow.com/questions/62654525/
+        emit-a-signal-from-another-class-to-main-class
+    and Singleton class at
+    https://refactoring.guru/design-patterns/singleton/python/example#example-0
+    """
+
+    enable_escape_signal = pyqtSignal(bool)
+    set_next_track_signal = pyqtSignal(int, int)
+    span_cells_signal = pyqtSignal(int, int, int, int)
+    add_track_to_playlist_signal = pyqtSignal(int, int, int, str)

app/helpers.py

@@ -1,3 +1,4 @@
+import functools
 import os
 import psutil
 import shutil
@@ -381,6 +382,22 @@ def show_warning(parent: QMainWindow, title: str, msg: str) -> None:
     QMessageBox.warning(parent, title, msg, buttons=QMessageBox.StandardButton.Cancel)
 
 
+def singleton(cls):
+    """
+    Make a class a Singleton class (see
+    https://realpython.com/primer-on-python-decorators/#creating-singletons)
+    """
+
+    @functools.wraps(cls)
+    def wrapper_singleton(*args, **kwargs):
+        if not wrapper_singleton.instance:
+            wrapper_singleton.instance = cls(*args, **kwargs)
+        return wrapper_singleton.instance
+
+    wrapper_singleton.instance = None
+    return wrapper_singleton
+
+
 def trailing_silence(
     audio_segment: AudioSegment,
     silence_threshold: int = -50,

app/musicmuster.py

@@ -69,6 +69,7 @@ import icons_rc  # noqa F401
 import music
 from models import Base, Carts, Playdates, PlaylistRows, Playlists, Settings, Tracks
 from config import Config
+from datastructures import MusicMusterSignals
 from playlists import PlaylistTab
 from ui.dlg_cart_ui import Ui_DialogCartEdit  # type: ignore
 from ui.dlg_TrackSelect_ui import Ui_Dialog  # type: ignore
@@ -238,20 +239,6 @@ class ImportTrack(QObject):
             self.finished.emit(self.playlist)
 
 
-class MusicMusterSignals(QObject):
-    """
-    Class for all MusicMuster signals. See:
-     - https://zetcode.com/gui/pyqt5/eventssignals/
-     - https://stackoverflow.com/questions/62654525/
-        emit-a-signal-from-another-class-to-main-class
-    """
-
-    enable_escape_signal = pyqtSignal(bool)
-    set_next_track_signal = pyqtSignal(int, int)
-    span_cells_signal = pyqtSignal(int, int, int, int)
-    add_track_to_playlist_signal = pyqtSignal(int, int, str)
-
-
 class PlaylistTrack:
     """
     Used to provide a single reference point for specific playlist tracks,
@@ -349,8 +336,6 @@ class Window(QMainWindow, Ui_MainWindow):
         self.previous_track_position: Optional[float] = None
         self.selected_plrs: Optional[List[PlaylistRows]] = None
 
-        self.signals = MusicMusterSignals()
-
         self.set_main_window_size()
         self.lblSumPlaytime = QLabel("")
         self.statusbar.addPermanentWidget(self.lblSumPlaytime)
@@ -379,6 +364,7 @@ class Window(QMainWindow, Ui_MainWindow):
         self.timer10.start(10)
         self.timer500.start(500)
         self.timer1000.start(1000)
+        self.signals = MusicMusterSignals()
         self.connect_signals_slots()
 
     def about(self) -> None:
@@ -731,7 +717,6 @@ class Window(QMainWindow, Ui_MainWindow):
         playlist_tab = PlaylistTab(
             musicmuster=self,
             playlist_id=playlist.id,
-            signals=self.signals,
         )
         idx = self.tabPlaylist.addTab(playlist_tab, playlist.name)
         self.tabPlaylist.setCurrentIndex(idx)
@@ -1065,7 +1050,7 @@ class Window(QMainWindow, Ui_MainWindow):
         with Session() as session:
             dlg = TrackSelectDialog(
                 session=session,
-                signals=self.signals,
+                new_row_number=self.active_tab().get_selected_row_number(),
                 playlist_id=self.active_tab().playlist_id,
             )
             dlg.exec()
@@ -1923,7 +1908,7 @@ class TrackSelectDialog(QDialog):
     def __init__(
         self,
         session: scoped_session,
-        signals: MusicMusterSignals,
+        new_row_number: int,
         playlist_id: int,
         *args,
         **kwargs,
@@ -1934,7 +1919,7 @@ class TrackSelectDialog(QDialog):
 
         super().__init__(*args, **kwargs)
         self.session = session
-        self.signals = signals
+        self.new_row_number = new_row_number
         self.playlist_id = playlist_id
         self.ui = Ui_Dialog()
         self.ui.setupUi(self)
@@ -1946,6 +1931,7 @@ class TrackSelectDialog(QDialog):
         self.ui.radioTitle.toggled.connect(self.title_artist_toggle)
         self.ui.searchString.textEdited.connect(self.chars_typed)
         self.track: Optional[Tracks] = None
+        self.signals = MusicMusterSignals()
 
         record = Settings.get_int_settings(self.session, "dbdialog_width")
         width = record.f_int or 800
@@ -1974,7 +1960,9 @@ class TrackSelectDialog(QDialog):
         track_id = None
         if track:
             track_id = track.id
-        self.signals.add_track_to_playlist_signal.emit(self.playlist_id, track_id, note)
+        self.signals.add_track_to_playlist_signal.emit(
+            self.playlist_id, self.new_row_number, track_id, note
+        )
 
     def add_selected_and_close(self) -> None:
         """Handle Add and Close button"""

app/playlistmodel.py

@@ -19,14 +19,15 @@ from PyQt6.QtGui import (
 )
 
 from config import Config
-from playlists import PlaylistTab
+from datastructures import MusicMusterSignals
+from dbconfig import scoped_session, Session
 from helpers import (
     file_is_unreadable,
 )
 from models import PlaylistRows, Tracks
 
-if TYPE_CHECKING:
+
-    from musicmuster import MusicMusterSignals
+HEADER_NOTES_COLUMN = 1
 
 
 class Col(Enum):
@@ -98,18 +99,15 @@ class PlaylistModel(QAbstractTableModel):
 
     def __init__(
         self,
-        playlist: PlaylistTab,
         playlist_id: int,
-        signals: "MusicMusterSignals",
         *args,
         **kwargs,
     ):
-        self.playlist = playlist
         self.playlist_id = playlist_id
-        self.signals = signals
         super().__init__(*args, **kwargs)
 
         self.playlist_rows: dict[int, PlaylistRowData] = {}
+        self.signals = MusicMusterSignals()
 
         self.signals.add_track_to_playlist_signal.connect(self.add_track)
 

app/playlists.py

@@ -36,8 +36,9 @@ from PyQt6.QtWidgets import (
     QStyleOption,
 )
 
-from config import Config
+from datastructures import MusicMusterSignals
 from dbconfig import Session, scoped_session
+from config import Config
 from helpers import (
     ask_yes_no,
     file_is_unreadable,
@@ -48,10 +49,8 @@ from helpers import (
     set_track_metadata,
 )
 from log import log
-
 from models import Playlists, PlaylistRows, Settings, Tracks, NoteColours
-
+from playlistmodel import PlaylistModel
-import playlistmodel
 
 if TYPE_CHECKING:
     from musicmuster import Window, MusicMusterSignals
@@ -66,9 +65,9 @@ class EscapeDelegate(QStyledItemDelegate):
     - checks with user before abandoning edit on Escape
     """
 
-    def __init__(self, parent, signals: "MusicMusterSignals") -> None:
+    def __init__(self, parent) -> None:
         super().__init__(parent)
-        self.signals = signals
+        self.signals = MusicMusterSignals()
 
     def createEditor(
         self,
@@ -80,7 +79,7 @@ class EscapeDelegate(QStyledItemDelegate):
         Intercept createEditor call and make row just a little bit taller
         """
 
-        self.signals.enable_escape_signal.emit(False)
+        signals.enable_escape_signal.emit(False)
         if isinstance(self.parent(), PlaylistTab):
             p = cast(PlaylistTab, self.parent())
         if isinstance(index.data(), str):
@@ -156,17 +155,15 @@ class PlaylistTab(QTableView):
         self,
         musicmuster: "Window",
         playlist_id: int,
-        signals: "MusicMusterSignals",
     ) -> None:
         super().__init__()
 
         # Save passed settings
         self.musicmuster = musicmuster
         self.playlist_id = playlist_id
-        self.signals = signals
 
         # Set up widget
-        self.setItemDelegate(EscapeDelegate(self, self.signals))
+        self.setItemDelegate(EscapeDelegate(self))
         self.setAlternatingRowColors(True)
         self.setSelectionMode(QAbstractItemView.SelectionMode.ExtendedSelection)
         self.setSelectionBehavior(QAbstractItemView.SelectionBehavior.SelectRows)
@@ -194,6 +191,7 @@ class PlaylistTab(QTableView):
             h_header.setStretchLastSection(True)
         # self.itemSelectionChanged.connect(self._select_event)
         # self.signals.set_next_track_signal.connect(self._reset_next)
+        self.signals = MusicMusterSignals()
         self.signals.span_cells_signal.connect(self._span_cells)
 
         # Call self.eventFilter() for events
@@ -205,7 +203,7 @@ class PlaylistTab(QTableView):
         # self.edit_cell_type: Optional[int]
 
         # Load playlist rows
-        self.setModel(playlistmodel.PlaylistModel(self, playlist_id, signals))
+        self.setModel(PlaylistModel(playlist_id))
         self._set_column_widths()
 
     # kae def __repr__(self) -> str:

test_playlistmodel.py

@@ -4,13 +4,12 @@ from app.models import (
 from app import playlistmodel
 from dbconfig import scoped_session
 
-
 def create_model_with_playlist_rows(
     session: scoped_session, rows: int
 ) -> "playlistmodel.PlaylistModel":
     playlist = Playlists(session, "test playlist")
     # Create a model
-    model = playlistmodel.PlaylistModel(playlist.id, None)
+    model = playlistmodel.PlaylistModel(playlist.id)
     for row in range(rows):
         plr = model._insert_row(session, row)
         newrow = plr.plr_rownum