Marsh Ray wrote:
On 12/01/2010 11:08 AM, Robert Ramey wrote:
It results in a better defined, more complete, more robust, more correct and cheaper to maintain and upgrade final product.
I would like to be able to say that from my own experience.
I'm basing my comments on my experience using a spirit xml parser for the serialization library input. I didn't (and still don't think parsing xml should be that hard. When I was faced with it my reaction was dread at having to do a small recurrsive descent or state machine parser for the umpteenth time.
When I had tried it, I referred to the calculator examples a lot. But they calculate the result and return just that! I wanted to build something very close to the parse tree, but had significant trouble figuring out how to construct the node types and pass them upwards.
I'll confess that using spirit was a lot harder than I thought it was going to be. This was mainly due to the fact the that declarative approach was sort of new to me. Then there was usage of things what I wasn't really familiar with at the time functors, binders, etc. But I also wanted to become familiar with these things. I did - with a little help - manage to get it working and was was extremely pleased with the result. There was the grammar displayed in a formal verifiable way totally separate from the other code - of which there was very little. It was much easier to be confident that it was correct - assuming spirit actually worked - which apparently it does.
The features for automatically constructing the return value were the most promoted by the documentation. It seemed to work great for things like ints and doubles, things that have an obvious primitive representation in C++. But the automatic facility seemed to just get in the way as soon as I wanted to return custom structs. There was the XML DOM example, but it was not simple enough for me.
Thanks, I'm joining the Spirit list now.
lol - I never hoped to be THAT persuasive. You might take a look at the xml_grammer code in the serialization library. I think it shows how valuable this tool can be. I turned a messy job into a work of art. Also note this made it easy to support a wide character version with ease. Finally, note that I have had my complaints and criticisms of spirit so I'm not really considered a member of the spirit "booster" team. I just took a look at the spirit parser cited in a previous email. This seems pretty good. I reminds me of my own experience - lots of cryptic functors and stuff and at the end - a very simple to understand listing of the actual JSON grammar. So it's a lot of work to setup but easy to maintain. Actually I see that he includes a JASON writer as well. If I had nothing else to do, I might be inclined to just make json_?archive classes out of these. Robert Ramey