Merge pull request #81 from realpython/pyqt-calculator-tutorial

jablonskidev · web-flow · commit 8aa902cbb906 · 2019-09-26T11:21:34.000-07:00
Pyqt calculator tutorial
diff --git a/pyqt-calculator-tutorial/examples/dialog.py b/pyqt-calculator-tutorial/examples/dialog.py
@@ -6,10 +6,10 @@
 
 from PyQt5.QtWidgets import QApplication
 from PyQt5.QtWidgets import QDialog
+from PyQt5.QtWidgets import QDialogButtonBox
+from PyQt5.QtWidgets import QFormLayout
 from PyQt5.QtWidgets import QLineEdit
 from PyQt5.QtWidgets import QVBoxLayout
-from PyQt5.QtWidgets import QFormLayout
-from PyQt5.QtWidgets import QDialogButtonBox
 
 
 class Dialog(QDialog):
diff --git a/pyqt-calculator-tutorial/examples/f_layout.py b/pyqt-calculator-tutorial/examples/f_layout.py
@@ -5,9 +5,9 @@
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
-from PyQt5.QtWidgets import QLineEdit
 from PyQt5.QtWidgets import QFormLayout
+from PyQt5.QtWidgets import QLineEdit
+from PyQt5.QtWidgets import QWidget
 
 app = QApplication(sys.argv)
 window = QWidget()
diff --git a/pyqt-calculator-tutorial/examples/g_layout.py b/pyqt-calculator-tutorial/examples/g_layout.py
@@ -5,9 +5,9 @@
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
-from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtWidgets import QGridLayout
+from PyQt5.QtWidgets import QPushButton
+from PyQt5.QtWidgets import QWidget
 
 app = QApplication(sys.argv)
 window = QWidget()
diff --git a/pyqt-calculator-tutorial/examples/h_layout.py b/pyqt-calculator-tutorial/examples/h_layout.py
@@ -5,17 +5,17 @@
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
-from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtWidgets import QHBoxLayout
+from PyQt5.QtWidgets import QPushButton
+from PyQt5.QtWidgets import QWidget
 
 app = QApplication(sys.argv)
 window = QWidget()
 window.setWindowTitle("QHBoxLayout")
 layout = QHBoxLayout()
-layout.addWidget(QPushButton("Right"))
-layout.addWidget(QPushButton("Center"))
 layout.addWidget(QPushButton("Left"))
+layout.addWidget(QPushButton("Center"))
+layout.addWidget(QPushButton("Right"))
 window.setLayout(layout)
 window.show()
 sys.exit(app.exec_())
diff --git a/pyqt-calculator-tutorial/examples/hello.py b/pyqt-calculator-tutorial/examples/hello.py
@@ -4,10 +4,10 @@
 
 import sys
 
-# 1. Import `QApplication`, and all the required widgets
+# 1. Import `QApplication` and all the required widgets
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
 from PyQt5.QtWidgets import QLabel
+from PyQt5.QtWidgets import QWidget
 
 # 2. Create an instance of QApplication
 app = QApplication(sys.argv)
diff --git a/pyqt-calculator-tutorial/examples/main_window.py b/pyqt-calculator-tutorial/examples/main_window.py
@@ -5,8 +5,8 @@
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QMainWindow
 from PyQt5.QtWidgets import QLabel
+from PyQt5.QtWidgets import QMainWindow
 from PyQt5.QtWidgets import QStatusBar
 from PyQt5.QtWidgets import QToolBar
 
diff --git a/pyqt-calculator-tutorial/examples/signals_slots.py b/pyqt-calculator-tutorial/examples/signals_slots.py
@@ -1,19 +1,22 @@
 # Filename: signals_slots.py
 
-"""Signals, and Slots example."""
+"""Signals and slots example."""
 
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
-from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtWidgets import QLabel
+from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtWidgets import QVBoxLayout
+from PyQt5.QtWidgets import QWidget
 
 
 def greeting():
     """Slot function."""
-    msg.setText("Hello World!")
+    if msg.text():
+        msg.setText("")
+    else:
+        msg.setText("Hello World!")
 
 
 app = QApplication(sys.argv)
diff --git a/pyqt-calculator-tutorial/examples/signals_slots_partial.py b/pyqt-calculator-tutorial/examples/signals_slots_partial.py
@@ -0,0 +1,36 @@
+# Filename: signals_slots_partial.py
+
+"""Signals and slots example."""
+
+import functools
+import sys
+
+from PyQt5.QtWidgets import QApplication
+from PyQt5.QtWidgets import QLabel
+from PyQt5.QtWidgets import QPushButton
+from PyQt5.QtWidgets import QVBoxLayout
+from PyQt5.QtWidgets import QWidget
+
+
+def greeting(who):
+    """Slot function."""
+    if msg.text():
+        msg.setText("")
+    else:
+        msg.setText(f"Hello {who}")
+
+
+app = QApplication(sys.argv)
+window = QWidget()
+window.setWindowTitle("Signals, and Slots")
+layout = QVBoxLayout()
+
+btn = QPushButton("Greet")
+btn.clicked.connect(functools.partial(greeting, "World!"))
+
+layout.addWidget(btn)
+msg = QLabel("")
+layout.addWidget(msg)
+window.setLayout(layout)
+window.show()
+sys.exit(app.exec_())
diff --git a/pyqt-calculator-tutorial/examples/v_layout.py b/pyqt-calculator-tutorial/examples/v_layout.py
@@ -5,9 +5,9 @@
 import sys
 
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QWidget
 from PyQt5.QtWidgets import QPushButton
 from PyQt5.QtWidgets import QVBoxLayout
+from PyQt5.QtWidgets import QWidget
 
 app = QApplication(sys.argv)
 window = QWidget()
diff --git a/pyqt-calculator-tutorial/pycalc/README.md b/pyqt-calculator-tutorial/pycalc/README.md
@@ -1,6 +1,6 @@
 # PyCalc
 
-PyCalc is a sample calculator implemented using Python 3, and with a [PyQt5](https://www.riverbankcomputing.com/static/Docs/PyQt5/introduction.html) GUI. PyCalc implements the most basic math operations, that is, division, multiplication, addition, and subtraction.
+PyCalc is a sample calculator implemented using Python 3 and with a [PyQt5](https://www.riverbankcomputing.com/static/Docs/PyQt5/introduction.html) GUI. PyCalc implements the most basic math operations, that is, division, multiplication, addition, and subtraction.
 
 PyCalc is intended to be a demonstrative example on how you can implement a Python + PyQt5 GUI application using the Model-View-Controller (MVC) pattern.
 
@@ -40,7 +40,7 @@ After running this command, you'll see PyCalc running on your screen.
 
 ## How to Use PyCalc
 
-To use PyCalc, you just need to enter a valid math expression using your mouse, and then press `Enter` or click on the `=` sign:
+To use PyCalc, you just need to enter a valid math expression using your mouse and then press `Enter` or click on the `=` sign:
 
 ![Screenshot](pycalc-howto.gif)
 
diff --git a/pyqt-calculator-tutorial/pycalc/pycalc.py b/pyqt-calculator-tutorial/pycalc/pycalc.py
@@ -10,20 +10,21 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 
-"""PyCalc is a simple calculator built using Python, and PyQt5."""
+"""PyCalc is a simple calculator built using Python and PyQt5."""
 
 import sys
+
 from functools import partial
 
-# Import QApplication, and the required widgets from PyQt5.QtWidgets
+# Import QApplication and the required widgets from PyQt5.QtWidgets
+from PyQt5.QtCore import Qt
 from PyQt5.QtWidgets import QApplication
-from PyQt5.QtWidgets import QMainWindow
-from PyQt5.QtWidgets import QWidget
-from PyQt5.QtWidgets import QVBoxLayout
 from PyQt5.QtWidgets import QGridLayout
 from PyQt5.QtWidgets import QLineEdit
+from PyQt5.QtWidgets import QMainWindow
 from PyQt5.QtWidgets import QPushButton
-from PyQt5.QtCore import Qt
+from PyQt5.QtWidgets import QVBoxLayout
+from PyQt5.QtWidgets import QWidget
 
 __version__ = "0.1"
 __author__ = "Leodanis Pozo Ramos"
@@ -41,12 +42,12 @@ def __init__(self):
         # Set some main window's properties
         self.setWindowTitle("PyCalc")
         self.setFixedSize(235, 235)
-        # Create, and set the central widget, and the general layout
+        # Set the central widget and the general layout
         self.generalLayout = QVBoxLayout()
         self._centralWidget = QWidget(self)
         self.setCentralWidget(self._centralWidget)
         self._centralWidget.setLayout(self.generalLayout)
-        # Create the display, and the buttons
+        # Create the display and the buttons
         self._createDisplay()
         self._createButtons()
 
@@ -88,11 +89,11 @@ def _createButtons(self):
             "+": (3, 3),
             "=": (3, 4),
         }
-        # Create the buttons, and add them to the grid layout
-        for btn_text, pos in buttons.items():
-            self.buttons[btn_text] = QPushButton(btn_text)
-            self.buttons[btn_text].setFixedSize(40, 40)
-            buttonsLayout.addWidget(self.buttons[btn_text], pos[0], pos[1])
+        # Create the buttons and add them to the grid layout
+        for btnText, pos in buttons.items():
+            self.buttons[btnText] = QPushButton(btnText)
+            self.buttons[btnText].setFixedSize(40, 40)
+            buttonsLayout.addWidget(self.buttons[btnText], pos[0], pos[1])
         # Add buttonsLayout to the general layout
         self.generalLayout.addLayout(buttonsLayout)
 
@@ -121,15 +122,15 @@ def evaluateExpression(expression):
     return result
 
 
-# Create a Controller class to connect the GUI, and the model
+# Create a Controller class to connect the GUI and the model
 class PyCalcCtrl:
     """PyCalc's Controller."""
 
     def __init__(self, model, view):
         """Controller initializer."""
         self._evaluate = model
         self._view = view
-        # Connect signals, and slots
+        # Connect signals and slots
         self._connectSignals()
 
     def _calculateResult(self):
@@ -146,10 +147,10 @@ def _buildExpression(self, sub_exp):
         self._view.setDisplayText(expression)
 
     def _connectSignals(self):
-        """Connect signals, and slots."""
-        for btn_text, btn in self._view.buttons.items():
-            if btn_text not in {"=", "C"}:
-                btn.clicked.connect(partial(self._buildExpression, btn_text))
+        """Connect signals and slots."""
+        for btnText, btn in self._view.buttons.items():
+            if btnText not in {"=", "C"}:
+                btn.clicked.connect(partial(self._buildExpression, btnText))
 
         self._view.buttons["="].clicked.connect(self._calculateResult)
         self._view.display.returnPressed.connect(self._calculateResult)
@@ -164,7 +165,7 @@ def main():
     # Show the calculator's GUI
     view = PyCalcUi()
     view.show()
-    # Create an instance of the model, and the controller
+    # Create instances of the model and the controller
     model = evaluateExpression
     PyCalcCtrl(model=model, view=view)
     # Execute calculator's main loop
