Question

CreateDocument(string templatePath)
{
    Document doc = OpenDocument(templatePath);
    Picture pic = GetLogo();
    AddLogo(doc, pic, templatePath);
}

AddLogo(Document doc, Picture logo, string templatePath)
{
    Picture placeholder = doc.FindLogoPlaceholder();
    if (placeholder.Size != logo.Size)
    {
        throw new ApplicationException(
            String.Format("Invalid template {0}, logo size: {1}, required: {2}",
                 templatePath, placeholder.Size, logo.Size
            ));
    }
}

Consider the above code as an example I just made up.

Notice that the only reason templatePath is passed into the AddLogo method is to facilitate exception generation.

I have something in my code today where I needed to do this, and it feels like a really nasty code smell to me. But I’m not too familiar with exception handling patterns and I don’t really see any better way to do it.

I’m wondering what your thoughts are and if there is a better pattern to dealing with situations like this.

Answer 1

Create the exception on a higher level:

CreateDocument(string templatePath)
{
    Document doc = OpenDocument(templatePath);
    Picture pic = GetLogo();
    try {
        AddLogo(doc, pic);
    } catch (InvalidLogoSize e) {
        throw new ApplicationException(
            String.Format("Invalid template {0}, logo size: {1}, required: {2}",
                 templatePath, e.pSize, e.lSize
            ));
    }
}

AddLogo(Document doc, Picture logo)
{
    Picture placeholder = doc.FindLogoPlaceholder();
    if (placeholder.Size != logo.Size)
    {
        throw new InvalidLogoSizeException(placeholder.Size, logo.Size);
    }
}