C# developers are torn between finding dynamics cool & useful and terrible & dangerous. In this talk I describe the basic use of dynamics and how it works before trying to show some usages of dynamics that can be both useful and even mighty. This Slide deck (in English) used at the HerbstCampus Conference in Nürnberg in September 2013 and provides you with an overview of the basic elements of the dynamics as well as examples of their usages. The presentation material as well as the demo code can be found on github at https://github.com/Timothep/Talk.Dynamics

1. Dynamisch und Gefährlich?
C# Dynamics in freier Wildbahn
Tim Bourguignon
Mathema Software GmbH
v1.1

2. Dynamics? Noooooooo....
Herbstcampus 2013 – Dynamisch und Gefährlich?
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3. Dynamics? Noooooooo....
Herbstcampus 2013 – Dynamisch und Gefährlich?
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4. Dynamics? Noooooooo....
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5. Dynamics? Noooooooo....
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6. Compiler says *meep*
string lang = "C#";
lang++;
int theAnswer = 42;
theAnswer.ToUpper();
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7. Compiler says *meep*
string lang = "C#";
lang++;
int theAnswer = 42;
theAnswer.ToUpper();
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8. Dynamics to the rescue
dynamic lang = "C#";
lang++;
dynamic theAnswer = 42;
theAnswer.ToUpper();
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9. Dynamics to the rescue
dynamic lang = "C#";
lang++;
dynamic theAnswer = 42;
theAnswer.ToUpper();
Relax Man,
he knows
what he's doing
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10. Dynamics to the rescue
dynamic lang = "C#";
lang++;
dynamic theAnswer = 42;
theAnswer.ToUpper();
Relax Man,
he knows
what he's doing
Herbstcampus 2013 – Dynamisch und Gefährlich?
… or not!
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11. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
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12. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
object calc = new Calculator();
int sum = calc.Add(10, 20);
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13. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
object calc = new Calculator();
int sum = calc.Add(10, 20);
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14. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
object calc = new Calculator();
int sum = calc.Add(10, 20);
object reflectionCalc = new Calculator();
Type calcType = reflectionCalc.GetType();
object result = calcType.InvokeMember("Add",
BindingFlags.InvokeMethod, null,
Activator.CreateInstance(calcType),
new object[] { 10, 20 });
int sum2 = Convert.ToInt32(result);
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15. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
object calc = new Calculator();
int sum = calc.Add(10, 20);
object reflectionCalc = new Calculator();
Type calcType = reflectionCalc.GetType();
object result = calcType.InvokeMember("Add",
BindingFlags.InvokeMethod, null,
Activator.CreateInstance(calcType),
new object[] { 10, 20 });
int sum2 = Convert.ToInt32(result);
Herbstcampus 2013 – Dynamisch und Gefährlich?
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16. What about 'object' or reflection?
Calculator calc = new Calculator();
int sum = calc.Add(10, 20);
object calc = new Calculator();
int sum = calc.Add(10, 20);
object reflectionCalc = new Calculator();
Type calcType = reflectionCalc.GetType();
object result = calcType.InvokeMember("Add",
BindingFlags.InvokeMethod, null,
Activator.CreateInstance(calcType),
new object[] { 10, 20 });
int sum2 = Convert.ToInt32(result);
Herbstcampus 2013
dynamic calc = new Calculator();
– Dynamisch und Gefährlich?
int sum = calc.Add(10, 20);
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17. Duck-Typing
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18. Duck-Typing
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19. Duck-Typing
• When I see a bird that
walks like a duck
swims like a duck
and quacks like a duck,
I call that bird a duck
James Whitcomb Riley
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20. Duck-Typing
• When I see a bird that
walks like a duck
swims like a duck
and quacks like a duck,
I call that bird a duck
James Whitcomb Riley
vs Be
• Look like
• Methods & Attributes vs Class
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21. Duck-Typing
• When I see a bird that
walks like a duck
swims like a duck
and quacks like a duck,
I call that bird a duck
James Whitcomb Riley
vs Be
• Look like
• Methods & Attributes vs Class
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22. Dynamic languages: IronPython - IronRuby
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23. Dynamic languages: IronPython - IronRuby
#Python script.py
def add(a, b):
return a + b
var pythonRuntime = Python.CreateRuntime();
dynamic pythonScript =
pythonRuntime.UseFile("script.py");
var result = pythonScript.add(100, 200)));
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24. Base objects & Tools
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25. Base objects & Tools
DynamicObject
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26. Base objects & Tools
DynamicObject
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ExpandoObject
28

27. Base objects & Tools
DynamicObject
ExpandoObject
ElasticObject
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28. Base objects & Tools
DynamicObject
ExpandoObject
ElasticObject
Gemini
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29. Frameworks
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30. Frameworks
Massive
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31. Frameworks
Massive
Nancy
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32. Frameworks
Massive
Nancy
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Simple.Data
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33. System.Dynamic.DynamicObject
• Exposes members at run time instead of at compile time
• Important methods
• TrySetMember
• TryGetMember
• Is called when a member of a dynamic class is requested and no
arguments are specified
• TryInvokeMember
• Is called when a member of a dynamic class is requested with
arguments
• Combining those functions in a smart way is the key
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34. System.Dynamic.ExpandoObject
• Represents an object whose members can be dynamically
added and removed at run time
• Demo
•
•
•
•
Simple ExpandoObject
Expando structure vs Xml structure
ExpandoToXml
Linq-to-Object
http://blogs.msdn.com/b/csharpfaq/archive/2009/10/01/dynamic-in-c-4-0-introducing-the-expandoobject.aspx
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35. ElasticObject
• Multi level dynamic object implementation using .NET 4.0
dynamic features, for fluent access of data types like XML
• Demo
• Expando vs Elastic
• Elastic-to-Xml
https://github.com/amazedsaint/ElasticObject
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36. Gemini
• „Brings the capabilities of a dynamic type system to C#“
• Demo
•
•
•
•
•
Members on the fly
Methods on the fly
Object graph
Responds to
Introspection
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37. NancyFx
• Lightweight WebFramework
• Demo
• Parameters
• Return object
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38. Massive
• Wrapper for DB tables that uses dynamics
• Create a class that wraps a table
• Query away
• Demo
• Usage
• Definition of TryGetMember
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39. Conclusion
• Objects
• Core Objects: DynamicObject, ExpandoObject
• Variations: ElasticObject, Gemini
• Usages: NancyFx, Massive, Simple.Data
• DTOs
• Architectural Flexibility
• API Design
• Think about using it!
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40. Ich freue mich auf Eure Fragen!
tim.bourguignon@mathema.de
about.me/timbourguignon
@timothep