What is C#. NET equivalent of Javascript's eval() ?

[Elliot]

I have a programs with thousands of variables. I need to perform complex operations on each of these variables that involves other variables.

What I would like to do is create a two column spreadsheet containing each of the variable names and the formula (stored as a string) used to calculate that variable's value. For each variable in the C# program, I would look up the string containing the formula and then calculate that formula.

Simple example:
Let's assume that there are three variables: x, y, and z.

x = 10
y = 20

I look up the formula for z and it returns the following string:

string = "x + y"

I am looking for a function that would do the equivalent of:

z = eval(string)
with the result that z would equal 30.

How can I do this in C#?

Many thanks in advance for any help.

[Elliot]

One further clarification:

Some of the formulas that I will using will call methods that I have defined.

So the string for z may be "x + y", but it might also be "NewMethod(x,y) "

[Plater]

If it can be done, it will probably involve System.Reflecti on

[Elliot]

Thanks for replying to my question. I looked up System.Reflecti on but have no idea how to implement it to solve this problem. Do you have a suggestion of how this System.Reflecti on might help in this case?

[Elliot]

Perhaps it would be helpful if I were to try to clarify what I'm looking to do:

Let's assume that we have a program with the following variables:

double x1 = 20;
double x2 = 30;
double y = 100;
string s = "y + NewMethod(x1, x2)";


Furthermore, let's assume that NewMethod() is some method that performs a calculation on its two parameters and returns a value of type double. For example, let's assume that NewMethod(20,30 ) would produce 610.23 as a result.

I am looking for a method (let's call it "Formula()" for demonstation purposes), such that:

z = Formula(s);

would produce the same result as:

z = y + NewMethod(x1, x2);

(i.e. z would be equal to 710.23)

[Alex Papadimoulis]

There is no "easy" way to do this in C#.

C# (and other .NET languages) are compiled into MSIL, and the Common Language Runtime (which executes MSIL) has no understanding of C#, VB, or any other .NET language. Interpreted languages (like JavaScript) have runtime engines that can understand and execute code.

That said, there are a few ways to handle this:

Write a parser/compiler for your specific needs - there are several tools (including the great GOLD Parsing System that can do all of the heavy lifting.

Use Windows Scripting Host - this is obviously Windows-specific, but it will enable you to execute Java or VB script and pass in your own objects. See msdn for more info.

Compile at run-time - this can get very tricky; there are plenty of helper classes within Reflection.Emit that can help you out.