Access a methods local variable value using a string containing the variable name in .Net

Question

I am attempting to get the value of a variable that has been declared locally in a method based on a string containing the variables name. I have been trying to use reflection as posted in multiple SO threads. The name of the variable is being stored in a table and accessed in the same method.

The problem I am having is seeing the methods local variable or the Method itself for that matter. I can see that value of a global variable as indicated in the code snippet below but I can not find the local variable in my methods. In other words the the variable TestrecordType is declared as a class variable and I can access it in any method wusing the code below. I need to access the variables in the local method where the code lives. Can anyone help me drill down to the methods level? Is it possible?

//10.07.2013 DRowe Collecting data for the json class
Corporate_Record clsCorporateRecord = new Corporate_Record();

// get the mapping for the class
ABC.Services.SYS.BmsBoardingEntryLayoutSpecificationCollection colLayoutSpecs = new ABC.Services.SYS.BmsBoardingEntryLayoutSpecificationCollection();
colLayoutSpecs = ABC.Services.SYS.BmsBoardingEntryLayoutSpecification.GetBySubClass("Corporate_Record");
foreach (ABC.Services.SYS.BmsBoardingEntryLayoutSpecification SpecRecord in colLayoutSpecs) {

    // Alter main class level (Global) variable
    TestrecordType = TestrecordType + " Now";

    string myproperty = SpecRecord.FieldName ;
    string myVariable = SpecRecord.MapToCodeVariable;
    string myType = SpecRecord.Type;

    // Can grab Main class variable values but not the local method variable values
    var result = this.GetType().GetField("TestrecordType").GetValue(this);

    clsCorporateRecord.GetType().GetProperty(myproperty).SetValue(clsCorporateRecord, result, null);

    MethodInfo mInfo = typeof(Worker).GetMethod("CreateCorporateRecord01");                         
}                    
myCollection.Corporate_Record.Add(clsCorporateRecord);
//10.07.2013 DRowe END

is there any way you can simplify this? Maybe just show [a portion of] the target class and what you're hoping to retrieve? — Brad Christie
– Brad Christie, Commented Oct 8, 2013 at 17:27
You should change your design to avoid needing this. Fundamentally reflection over local variables either won't work, or will require crazy code. — Jon Skeet
– Jon Skeet, Commented Oct 8, 2013 at 17:29
Agreed I am working in a huge application that was developed years ago and do not have the option of a rewrite. — Dan Rowe
– Dan Rowe, Commented Oct 8, 2013 at 17:32
"Local variable names are not persisted in metadata." - MSDN. I don't see how you will be able to get them with reflection. — Mike Zboray
– Mike Zboray, Commented Oct 8, 2013 at 17:37

Chris Tavares · Accepted Answer · 2013-10-08 17:29:15Z

5

Local variables aren't representing in reflection. You can see globals because they're members of a type. Locals, however, are just slots on the current stack, and that stack isn't exposed to the reflection APIs.

The only place that the call stack is exposed programmatically is in the stack trace in an exception. You could throw an exception deliberately, catch it, and pick through the stack trace. But it would be a bad, bad, idea, and extremely slow.

answered Oct 8, 2013 at 17:29

Chris Tavares

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2 Comments

Lasse V. Karlsen Over a year ago

Note that you can get the stack trace of the current location without having to throw an exception, by constructing an instance of the Stacktrace class. It's still slow though.

Dan Rowe Over a year ago

That's a bummer. My alternative is to replace all the variables in the local method with a dictionary. Based on this code will be extensive and prone to Cut and paste errors

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