What do these properties mean in Mono.Cecil?

Question

I am using Lokad shared libraries, which in turn depends on Mono.Cecil.

I am a little confused what the following properties mean (they are to do with .NET internals and thus have equivalent .NET internals):

• PackingSize (they are to do with types as it is in TypeDefinition).
• Mvid (in ModuleDefinition).
• ExplicitThis (something to do with the this keyword I know, but in MethodDefinition).
• CallingConvention.
• GetSentinel (a method which returns int in MethodReference).
• RVA.
• SemanticsAttribute.
• IsHideBySig.

Any idea what these mean/do?

Answer 1

I'm not too familiar with Cecil, but the majority of those items are related to the IL file. Here are some answers - all taken from Serge Lidin's book: Expert .Net 2.0 IL Assembler.

• Packing Size = The alignment factor in bytes. Must be set to 0 or a power of 2 from 1 to 128. (in the class layout metadata table) (p122)

• Mvid = globally unique identifier, assigned to the module as it is generated (or module version id). (in the module metadata table) (p105)

• Explicit This = Method call signature. The first explicitly specified parameter is the instance pointer. The ILAsm keywork is explicit. (p159)

• CallingConvention = the first byte of a signature identifies the type of the signature, which for historical reasons is called the calling convention of the signature. (ex: default, vararg, field, localsig, property, unmgd, hasthis, explicitthis) p158-159

• GetSentinel = most likely has to do with the sentinel modifier, which signifies the beginning of optional arguments supplied for a vararg method call. (p152)

• RVA = Relative virtual address: the address of an item once it has been loaded into memory, with the base address of the image file subtracted from it - in other words, the offset of an item within the image file loaded into memory. (p42)

• SemanticsAttribute - most likely something to do with the MethodSemantics table, which connects events and properties with their associated methods and provides information regarding the type of association. A Semantic can be a setter, getter, other (property) or addon, removeon or fire (event) p317

• IsHideBySig - the method hides all methods of the parent classes that have a matching signature and name (as opposed to having a matching name only). p188