Clean Code: Readable Dependency Injection suggestions?
I have a project that adds elements to an AutoCad drawing. I noticed that I was starting to write the same ten lines of code in multiple methods (only showing two for simplicity).
**Initial Implementation:**
You will notice that the only thing that really changes is adding a Line instead of a Circle.
[CommandMethod("Test", CommandFlags.Session)]
public void Test()
{
AddLineToDrawing();
AddCircleToDrawing();
}
private void AddLineToDrawing()
{
using (DocumentLock lockedDocument = Application.DocumentManager.MdiActiveDocument.LockDocument())
{
using (Database database = Application.DocumentManager.MdiActiveDocument.Database)
{
using (Transaction transaction = database.TransactionManager.StartTransaction())//Start the transaction
{
//Open the block table for read
BlockTable blockTable = transaction.GetObject(database.BlockTableId, OpenMode.ForRead) as BlockTable;
//Open the block table record model space for write
BlockTableRecord blockTableRecord = (BlockTableRecord)transaction.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
Line line = new Line(new Point3d(0, 0, 0), new Point3d(10, 10, 0));
blockTableRecord.AppendEntity(line);
transaction.AddNewlyCreatedDBObject(line, true);
transaction.Commit();
}
}
}
}
private void AddCircleToDrawing()
{
using (DocumentLock lockedDocument = Application.DocumentManager.MdiActiveDocument.LockDocument())
{
using (Database database = Application.DocumentManager.MdiActiveDocument.Database)
{
using (Transaction transaction = database.TransactionManager.StartTransaction())//Start the transaction
{
//Open the block table for read
BlockTable blockTable = transaction.GetObject(database.BlockTableId, OpenMode.ForRead) as BlockTable;
//Open the block table record model space for write
BlockTableRecord blockTableRecord = (BlockTableRecord)transaction.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
Circle circle = new Circle(new Point3d(0, 0, 0), new Vector3d(0, 0, 0), 10);
blockTableRecord.AppendEntity(circle);
transaction.AddNewlyCreatedDBObject(circle, true);
transaction.Commit();
}
}
}
}
**Injection:** This approached removed the duplication of code, but I think the readability is poor.
[CommandMethod("Test", CommandFlags.Session)]
public void Test()
{
PerformActionOnBlockTable(new CircleDrawer());
PerformActionOnBlockTable(new LineDrawer());
}
public interface IDraw
{
DBObject DrawObject(BlockTableRecord blockTableRecord);
}
public class CircleDrawer : IDraw
{
public DBObject DrawObject(BlockTableRecord blockTableRecord)
{
Circle circle = new Circle(new Point3d(0, 0, 0), new Vector3d(0, 0, 0), 10);
blockTableRecord.AppendEntity(circle);
return circle;
}
}
public class LineDrawer : IDraw
{
public DBObject DrawObject(BlockTableRecord blockTableRecord)
{
Line line = new Line(new Point3d(0, 0, 0), new Point3d(10, 10, 0));
blockTableRecord.AppendEntity(line);
return line;
}
}
private void PerformActionOnBlockTable(IDraw drawer)
{
using (DocumentLock lockedDocument = Application.DocumentManager.MdiActiveDocument.LockDocument())
{
using (Database database = Application.DocumentManager.MdiActiveDocument.Database)
{
using (Transaction transaction = database.TransactionManager.StartTransaction())//Start the transaction
{
//Open the block table for read
BlockTable blockTable = transaction.GetObject(database.BlockTableId, OpenMode.ForRead) as BlockTable;
//Open the block table record model space for write
BlockTableRecord blockTableRecord = (BlockTableRecord)transaction.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
DBObject newObject = drawer.DrawObject(blockTableRecord);
transaction.AddNewlyCreatedDBObject(newObject, true);
transaction.Commit();
}
}
}
}
**Injecting Func<>:** This seemed to give me a similar result, with better readability.
[CommandMethod("Test", CommandFlags.Session)]
public void Test()
{
PerformActionOnBlockTable(AddLineToDrawing);
PerformActionOnBlockTable(AddCircleToDrawing);
}
private void PerformActionOnBlockTable(Func<BlockTableRecord, DBObject> action)
{
using (DocumentLock lockedDocument = Application.DocumentManager.MdiActiveDocument.LockDocument())
{
using (Database database = Application.DocumentManager.MdiActiveDocument.Database)
{
using (Transaction transaction = database.TransactionManager.StartTransaction())//Start the transaction
{
//Open the block table for read
BlockTable blockTable = transaction.GetObject(database.BlockTableId, OpenMode.ForRead) as BlockTable;
//Open the block table record model space for write
BlockTableRecord blockTableRecord = (BlockTableRecord)transaction.GetObject(blockTable[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
DBObject newObject = action(blockTableRecord);
transaction.AddNewlyCreatedDBObject(newObject, true);
transaction.Commit();
}
}
}
}
private DBObject AddLineToDrawing(BlockTableRecord blockTableRecord)
{
Line line = new Line(new Point3d(0, 0, 0), new Point3d(10, 10, 0));
blockTableRecord.AppendEntity(line);
return line;
}
private DBObject AddCircleToDrawing(BlockTableRecord blockTableRecord)
{
Circle circle = new Circle(new Point3d(0, 0, 0), new Vector3d(0, 0, 0), 10);
blockTableRecord.AppendEntity(circle);
return circle;
}
I can honestly say that I have not done much with DI, so I'm quite new to this. Could any of you more experienced developers give me Pro's/Con's of the two different approaches? Is there anything in the last approach that's a red flag? It seems to be more readable than the second approach. Maybe I'm not even completely understanding injection... Thanks in advance for you input!
