Re: Adding more information to exceptions

[Ali Çehreli]

On 01/29/2013 12:32 PM, Vladimir Panteleev wrote:

> I would like to add some information to any exceptions thrown inside the
> loop's body (e.g. whatever std.conv.to may throw), in our case the line
> number.
Here is a RAII idea that takes advantage of exception chaining without 
directly using the 'next' parameter. It constructs a LineInfo object 
ready to throw in its destructor unless specifically told that it is not 
necessary anymore.

import std.stdio;
import std.string;
import std.conv;

void main()
{
    auto lines = [ "42", "100", "hello" ];

    int[] numbers;

    struct LineInfo
    {
        size_t lineNumber;
        bool allIsGood = false;

        ~this()
        {
            if (!allIsGood) {
                throw new Exception(format("Line number: %s", lineNumber));
            }
        }
    }

    foreach (lineNumber, line; lines) {
        auto info = LineInfo(lineNumber);
        numbers ~= to!int(line);
        info.allIsGood = true;
    }
}

Ali