Using Reflection.Emit to match existing constructor
- by yodaj007
First, here is the C# code and the disassembled IL:
public class Program<T>
{
private List<T> _items;
public Program(T x, [Microsoft.Scripting.ParamDictionary] Microsoft.Scripting.IAttributesCollection col)
{
_items = new List<T>();
_items.Add(x);
}
}
Here is the IL of that constructor:
.method public hidebysig specialname rtspecialname
instance void .ctor(!T x,
class [Microsoft.Scripting]Microsoft.Scripting.IAttributesCollection col) cil managed
{
.param [2]
.custom instance void [Microsoft.Scripting]Microsoft.Scripting.ParamDictionaryAttribute::.ctor() = ( 01 00 00 00 )
// Code size 34 (0x22)
.maxstack 8
IL_0000: ldarg.0
IL_0001: call instance void [mscorlib]System.Object::.ctor()
IL_0006: nop
IL_0007: nop
IL_0008: ldarg.0
IL_0009: newobj instance void class [mscorlib]System.Collections.Generic.List`1<!T>::.ctor()
IL_000e: stfld class [mscorlib]System.Collections.Generic.List`1<!0> class Foo.Program`1<!T>::_items
IL_0013: ldarg.0
IL_0014: ldfld class [mscorlib]System.Collections.Generic.List`1<!0> class Foo.Program`1<!T>::_items
IL_0019: ldarg.1
IL_001a: callvirt instance void class [mscorlib]System.Collections.Generic.List`1<!T>::Add(!0)
IL_001f: nop
IL_0020: nop
IL_0021: ret
} // end of method Program`1::.ctor
I am trying to understand the IL code by emitting it myself. This is what I have managed to emit:
.method public hidebysig specialname rtspecialname
instance void .ctor(!T A_1,
class [Microsoft.Scripting]Microsoft.Scripting.IAttributesCollection A_2) cil managed
{
// Code size 34 (0x22)
.maxstack 4
IL_0000: ldarg.0
IL_0001: call instance void [mscorlib]System.Object::.ctor()
IL_0006: ldarg.0
IL_0007: newobj instance void class [mscorlib]System.Collections.Generic.List`1<!T>::.ctor()
IL_000c: stfld class [mscorlib]System.Collections.Generic.List`1<!0> class MyType<!T>::_items
IL_0011: ldarg.0
IL_0012: ldfld class [mscorlib]System.Collections.Generic.List`1<!0> class MyType<!T>::_items
IL_0017: ldarg.s A_1
IL_0019: nop
IL_001a: nop
IL_001b: nop
IL_001c: callvirt instance void class [mscorlib]System.Collections.Generic.List`1<!T>::Add(!0)
IL_0021: ret
} // end of method MyType::.ctor
There are a few differences that I just can't figure out. I'm really close...
How do I take care of the parameter attribute (ParamDictionaryAttribute)? I can't find a 'custom' opcode.
Is the .param [2] important? How do I emit that?
Why is the C# code stack size 8, while my emitted version is 4? Is this important?
