Generating Data Access
Assemblies with IronRuby
Rob Rowe
Twitter: @rippinrobr
Blog: rob-rowe.blogspot.com
Why?
• Make tedious changes easier and quicker
• Create code based off of data specs from outside
sources
• Wanted to learn Ruby
• Used IronRuby to access to .NET libraries such
as System.Reflection.Emit
• Generate a DLL without compilation
What is IronRuby?
• An implementation of Ruby 1.8.x
• Built on top of .NET’s Dynamic Language
Runtime
• Allows IronRuby to access .NET objects such as
System.Reflection or any other .NET library
• Easy to ‘load’ .NET libraries
Overview
Consuming Application – ASP.NET MVC 2
Generated Code – Models DLL and C# Domain/Service layer
Field Definitions Tables
Creating a .NET Assembly
1.
2.
3.
4.
5.
Establish Assembly characteristics
Create the new Assembly
Define the Module
Create the Class
Create the Properties
a.
b.
c.
d.
Create the backing field
Create the Property
Create Getter
Create Setter
6. Save the Assembly
1. Establish Assembly Characteristics
• Create an instance of the
System.Reflection.AssemblyName class
• Set Version
• Set Name
• Can set CultureInfo, Crypto KeyPair among as
well as other settings
2. Create the new Assembly
• Creates the assembly in memory
• The first parameter is the AssemblyName object
from step 1.
• Second parameter sets the permissions for the
assembly. Here we can run it and save it to the
file system.
• Returns an AssemblyBuilder Object. Used to
create the module for the assembly.
3. Define the Module
• Each .NET assembly must have at least one
module
• ‘Container’ for classes, interfaces, etc.
• Parameters:
1. Name of the module
2. Name of the DLL
3. false – so no symbols are created
4. Create the Class
• @mod_builder is the object returned when we
created the module. Creates the class ‘under’ the
module
• First parameter is fully qualified name of the
class
• Second parameter is used to set public, static,
etc.
• Returned TypeBuilder object is used to create
the class’s fields and properties.
5a. Create Fields
•
•
•
•
Must create a field for each property
Creates a private field used by the getter/setters
Uses the class’s TypeBuilder object
Parameters
▫ Defines the name
▫ CLR Type
▫ Sets Access level
5b. Create Properties
• Creates the Property’s TypeObject used for
getter/setters
• Parameters:
▫
▫
▫
▫
Property Name
Says there’s a default value for this property
The CLR Type
Since there are no parameters for our properties
we pass in null
5c. Create Getter – Prep Work
• Creates the Get method TypeObject
• DefineMethod’s parameters
▫
▫
▫
▫
Name of the method
Attributes for the method
Return type (CLR type)
Parameters to the method – none for getter
• GetILGenerator - creates the object that is used
to create the IL code
5c. Create Getter – Method Body
• OpCodes.Ldarg_0 – loads the first argument
on the stack which is ‘this’ in our case.
• OpCodes.Ldfld – pushes the value of the
private field onto the stack.
• OpCodes.Ret – the returns the last item on the
evaluation stack, the value of the private field.
5d. Create Setter – Parameters
• Constructs the Type array needed for the setter’s
method parameters
• The type added to the list is the CLR type of the
property
• Need to use a generic list to create the necessary
CLR array
• Use List<T>’s ToArray method to get around
CLR array type issues
5d. Create Setter – Method Body
• OpCodes.Ldarg_0 – loads the first argument
on the stack which is ‘this’ in our case.
• OpCodes.Ldarg_1 - loads the setter
parameter onto the stack
• OpCodes.Stfld – sets the value of private_field
to the value of the item popped from the stack.
• OpCodes.Ret – adds the return statement.
5e. Finalizing Property Creation
• Need to associate the getter and setter with our
new property
• Use the property TypeBuilder to associate the
two method’s TypeBuilder objects with the IL we
just created
6. Saving the Assembly
• The assembly is saved to the file system by using
the AssemblyBuilder object’s Save method
• Once it has been saved we can use our new
Models DLL like any other assembly.
Resources/Contact Info
•
•
•
•
Robert.rowe@duke.edu
Twitter: @rippinrobr
Blog: rob-rowe@blogspot.com
Code:
https://bitbucket.org/robrowe/ironrubyassembl
ybuilder
• Books: IronRuby Unleashed, Programming
Ruby (AKA The Pickaxe Book)