Re: Saving a table in file

["Luciano de Souza" <luchyanus@...>]

If I understood: to serialize is to convert tables into a string 
representation and, without some significant code, we cannot do it.

I will study everything you sent me. But now I need the simplest solution. I 
am studying IUP. I am trying to save some data in a file to test more 
realistically the features I programed. Up to now, the simplest way to save 
tables, as I cold see, the way we write less lines, it seems to be using 
XML. Am I right?

I only want to save a table. Firstly, I tried to use Sqlite3. I learnt the 
SQL sintax. I read something about normalized databases. I read... I read... 
But although Sqlite is really simple, something always is wrong. It seemed 
to be very simple. But I got errors without error messages.

After I tried to use lots of coma separated files, but it became hard.

I tried to use XML and the results were OK to write values. To read values 
semms to be a little bit harder. As I could see, the simplest way to store a 
table is to use Luaxml.

Actually, I tried to create my tables in Pascal:

type

wolrd = record

country: string;

city: string;

end;

With Plua and the interface with Lua stack, I could add and remove values in 
a table stored in a file. But it's a awful way, I know.

In Python, we have something like:

import shelve

file = shelve.open('countries.db')

For this point on, "file" can be used as a table. After trying so many 
different things, only to save some data collected by a IUP interface, 
perhaps I am impacient. I am not lazy, believe.

My options area:

1. to discover how to handle with the Sqlite erros;

2. to undestand better Luaxml. I found so few examples that I didn't mature 
the idea. Lua has good manuals, but I think Luaxml is not one of then.

If I invest in this strategies of serialization, I will to learn more, and 
more, and more... I know to learn is one of the best things in the wolrd, 
but at this moment I need to conquer something.

That's the greatest problem of beginners. You are right in everything you 
said. I think the problem is me.



----- Original Message ----- 
From: "Matthias Kluwe" <mkluwe@gmail.com>
To: "Lua list" <lua@bazar2.conectiva.com.br>
Sent: Sunday, March 07, 2010 3:21 PM
Subject: Re: Saving a table in file


Hi!

2010/3/7 Luciano de Souza <luchyanus@predialnet.com.br>:
> Hello,
>
> Suppose we have the following table:
>
> t =
>
> {
>
> {country = 'Brazil', city = 'São Paulo'},
>
> {country = 'Italy', city = 'Napoli'},
>
> {country = 'France', city = 'Nantes'},
>
> {country = 'United States', city = 'Chicago'}
>
> }
>
> I know how to add or remove elements. But, how to save it in a file?

Your problem is known as "serialization"
(http://en.wikipedia.org/wiki/Serialization, someone may add a Lua
example here). Take a look at http://www.lua.org/pil/12.1.html or
http://lua-users.org/wiki/TableSerialization.

Regards,
Matthias