Refactor package installation (#8)

Author: maekind

README.md

@@ -32,12 +32,31 @@ migration flow.
 
 ## 📦 Installation
 
-You can install this package using pip:
+You can install this package using pip with different feature sets:
+
+### Standard Installation (Validation Only)
+For basic migration validation without graph visualization:
+
+```bash
+pip install pylembic[standard]
+```
+
+### Full Installation (All Features)
+For complete functionality including graph visualization:
+
+```bash
+pip install pylembic[all]
+```
+
+### Basic Installation
+You can also install the basic package without optional dependencies:
 
 ```bash
 pip install pylembic
 ```
 
+**Note:** The `show_graph` functionality requires the `[all]` installation option as it depends on `matplotlib`. The core validation features (including branch detection) work with all installation options as they use `networkx` which is included by default.
+
 ## ⚙️ Usage
 
 ### 🧪 Testing

pyproject.toml

@@ -10,19 +10,24 @@ license = { file = "LICENSE" }
 requires-python = ">=3.11"
 
 dependencies = [
-    "alembic==1.16.4",
-    "matplotlib==3.10.3",
+    "alembic==1.16.5",
     "networkx==3.5",
-    "typer==0.16.0",
+    "typer==0.17.4",
+]
+
+[project.optional-dependencies]
+standard = []
+all = [
+    "matplotlib==3.10.6",
 ]
 
 [tool.uv]
 dev-dependencies = [
-    "pytest-cov==6.2.1",
-    "pytest-mock==3.14.1",
-    "pytest==8.4.1",
-    "ruff==0.12.4",
-    "pre-commit==4.2.0",
+    "pytest-cov==6.3.0",
+    "pytest-mock==3.15.0",
+    "pytest==8.4.2",
+    "ruff==0.12.12",
+    "pre-commit==4.3.0",
 ]
 
 [tool.ruff]

src/pylembic/cli.py

@@ -56,7 +56,11 @@ def show_graph(
     validator = Validator(migrations_path)
 
     typer.echo("Visualizing migration graph...")
-    validator.show_graph()
+    try:
+        validator.show_graph()
+    except ImportError as exc:
+        typer.secho(str(exc), fg=typer.colors.RED)
+        raise typer.Exit(1) from exc
 
 
 if __name__ == "__main__":

src/pylembic/validator.py

@@ -1,7 +1,14 @@
 from os import path
 
-import matplotlib.pyplot as plt
 import networkx as nx
+
+try:
+    import matplotlib.pyplot as plt
+
+    HAS_MATPLOTLIB = True
+except ImportError:
+    HAS_MATPLOTLIB = False
+
 from alembic.config import Config
 from alembic.script import ScriptDirectory
 from alembic.util import CommandError
@@ -183,6 +190,12 @@ def show_graph(self) -> None:
         """
         Visualizes the migration dependency graph.
         """
+        if not HAS_MATPLOTLIB:
+            raise ImportError(
+                "Graph visualization requires matplotlib. "
+                "Install with 'pip install pylembic[all]' to enable this feature."
+            )
+
         plt.figure(figsize=(12, 8))
         pos = nx.spring_layout(self.graph)
         labels = {node: f"{node[:8]}" for node in self.graph.nodes}  # Short revision ID