Question

I know the title is probably really hard to understand, it was hard to think of a proper title, but here’s the essence of what I want to do.

Basically I want to have a method like this:

void Validate(bool validation)
{
    if (!validation)
    {
        throw new Exception();
    }
}

And then I want to call it like:

try
{
    Validate(1 > 2);
}
catch (Exception e)
{
    // This is where I would output the error to the user
}

I want to get the 1 > 2 part as a string without defining it as one elsewhere, or evaluating a string to a bool, or using predicates, or using external methods. Ideally this would be done via reflection. I’ll also take suggestions on a better way to do what I want to do. Assume that the bool could be anything: 1 > 2, "cheese" != "ham", objectA == objectB, etc.

Answer 1

You can’t. Well, perhaps you happen to can (in Python, one could hack something like this together, I suppose, although it wouldn’t be pretty, wouldn’t work reliably and would require having the source code at hand), but generally:

• You don’t have string repesentations of code at runtime.
• Arguments (expressions) are evaluated before the function is called.
• The evaluation yields nothing but a lone bool that doesn’t remember the slightest bit about where it came from.

Before you’re looking for some nasty nasty hack to emulate this, check if it isn’t easier to add a string literal during compilation.