merge

examples/calculator.py

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+from contextlib import suppress
+from decimal import Decimal
+from typing import ClassVar
+
+from textual import events
+from textual.app import App, ComposeResult
+from textual.containers import Container
+from textual.css.query import NoMatches
+from textual.reactive import var
+from textual.widgets import Button, Static
+
+
+class CalculatorApp(App):
+    """A working 'desktop' calculator."""
+
+    CSS_PATH = "calculator.css"
+
+    numbers = var("0")
+    show_ac = var(True)
+    left = var(Decimal("0"))
+    right = var(Decimal("0"))
+    value = var("")
+    operator = var("plus")
+
+    NAME_MAP: ClassVar = {
+        "asterisk": "multiply",
+        "slash": "divide",
+        "underscore": "plus-minus",
+        "full_stop": "point",
+        "plus_minus_sign": "plus-minus",
+        "percent_sign": "percent",
+        "equals_sign": "equals",
+        "minus": "minus",
+        "plus": "plus",
+    }
+
+    def watch_numbers(self, value: str) -> None:
+        """Called when numbers is updated."""
+        # Update the Numbers widget
+        self.query_one("#numbers", Static).update(value)
+
+    def compute_show_ac(self) -> bool:
+        """Compute switch to show AC or C button"""
+        return self.value in ("", "0") and self.numbers == "0"
+
+    def watch_show_ac(self, show_ac: bool) -> None:
+        """Called when show_ac changes."""
+        self.query_one("#c").display = not show_ac
+        self.query_one("#ac").display = show_ac
+
+    def compose(self) -> ComposeResult:
+        """Add our buttons."""
+        with Container(id="calculator"):
+            yield Static(id="numbers")
+            yield Button("AC", id="ac", variant="primary")
+            yield Button("C", id="c", variant="primary")
+            yield Button("+/-", id="plus-minus", variant="primary")
+            yield Button("%", id="percent", variant="primary")
+            yield Button("÷", id="divide", variant="warning")
+            yield Button("7", id="number-7")
+            yield Button("8", id="number-8")
+            yield Button("9", id="number-9")
+            yield Button("x", id="multiply", variant="warning")
+            yield Button("4", id="number-4")
+            yield Button("5", id="number-5")
+            yield Button("6", id="number-6")
+            yield Button("-", id="minus", variant="warning")
+            yield Button("1", id="number-1")
+            yield Button("2", id="number-2")
+            yield Button("3", id="number-3")
+            yield Button("+", id="plus", variant="warning")
+            yield Button("0", id="number-0")
+            yield Button(".", id="point")
+            yield Button("=", id="equals", variant="warning")
+
+    def on_key(self, event: events.Key) -> None:
+        """Called when the user presses a key."""
+
+        def press(button_id: str) -> None:
+            with suppress(NoMatches):
+                self.query_one(f"#{button_id}", Button).press()
+
+        key = event.key
+        if key.isdecimal():
+            press(f"number-{key}")
+        elif key == "c":
+            press("c")
+            press("ac")
+        else:
+            button_id = self.NAME_MAP.get(key)
+            if button_id is not None:
+                press(self.NAME_MAP.get(key, key))
+
+    def on_button_pressed(self, event: Button.Pressed) -> None:
+        """Called when a button is pressed."""
+
+        button_id = event.button.id
+        assert button_id is not None
+
+        def do_math() -> None:
+            """Does the math: LEFT OPERATOR RIGHT"""
+            try:
+                if self.operator == "plus":
+                    self.left += self.right
+                elif self.operator == "minus":
+                    self.left -= self.right
+                elif self.operator == "divide":
+                    self.left /= self.right
+                elif self.operator == "multiply":
+                    self.left *= self.right
+                self.numbers = str(self.left)
+                self.value = ""
+            except Exception:
+                self.numbers = "Error"
+
+        if button_id.startswith("number-"):
+            number = button_id.partition("-")[-1]
+            self.numbers = self.value = self.value.lstrip("0") + number
+        elif button_id == "plus-minus":
+            self.numbers = self.value = str(Decimal(self.value or "0") * -1)
+        elif button_id == "percent":
+            self.numbers = self.value = str(Decimal(self.value or "0") / Decimal(100))
+        elif button_id == "point":
+            if "." not in self.value:
+                self.numbers = self.value = (self.value or "0") + "."
+        elif button_id == "ac":
+            self.value = ""
+            self.left = self.right = Decimal(0)
+            self.operator = "plus"
+            self.numbers = "0"
+        elif button_id == "c":
+            self.value = ""
+            self.numbers = "0"
+        elif button_id in ("plus", "minus", "divide", "multiply"):
+            self.right = Decimal(self.value or "0")
+            do_math()
+            self.operator = button_id
+        elif button_id == "equals":
+            if self.value:
+                self.right = Decimal(self.value)
+            do_math()
+
+
+if __name__ == "__main__":
+    CalculatorApp().run()