As Ned points out starting with something like XML is neater than
working back to it. C structures parse very nicely, but XML parsers are
everywhere. All you need to build is a code generator to optionally
compile SQL or C/C++ from the XML data definition, a simple task.
JS
Ned Batchelder wrote:
I my experience, the best approach is to create a description of your data
in a form that is good for being parsed and feeding into a code generator.
C structures are not good for this, they are good for being compiled into
executable code.
I would create a data description, and use it to generate the SQL and the C
structures. The data description could be whatever you find convenient: I
use XML, but anything will do so long as it is expressive enough for you and
you can parse it.
I use a code generation tool called Cog (http://nedbatchelder.com/code/cog)
to generate the code itself.
--Ned.
http://nedbatchelder.com
-----Original Message-----
From: John Stanton [mailto:[EMAIL PROTECTED]
Sent: Monday, 17 October, 2005 10:40 AM
To: sqlite-users@sqlite.org
Subject: Re: [sqlite] Question about automatic schema creation from custom
data-strucutre for persistence storage
I addressed this some time back in a C program which dynamically
generates XML. Generating SQL would be an option.
By building a table with a keyname for each data element and a pointer
to a data item the output structure can be assembled. As a wise person
once told me "There is no problem in CS which cannot be solved by yet
another level of indirection".
In my case I also added a function pointer so that callbacks could be
used. With XML the table is actually a transformation of the DTD so
that the result is guaranteed to be "well formed". If the table were
compiled from the data structure then a similar integrity could be assured.
This method would require a few lines of code, but you would only need
to do it once as opposed to writing code for each data structure.
JS
Dan Kennedy wrote:
As far as I know C++ has no introspection capability so the answer
is probably no. Unless you want to parse your header file yourself,
or something like that.
With Java or another high-level programming language that supports
introspection it would be possible I think.
"Rajan, Vivek K" <[EMAIL PROTECTED]> wrote:
Hello-
Has anyone had experience with automatically creating schema from a
custom data-structure for persistence storage using SQLite? So, in my
C/C++ program I have the following type of data-structure:
struct _trace {
std::string name;
std::string prop;
std:string object;
int a;
double b;
};
std::vector _myPath;
Now, let's say I want to write and read _myPath data-structure
(persistence) in SQLite database.
My questions:
- Is there a mechanism to dynamically create a schema on-the-fly from
the data-structure?
- Essentially a capability to store any custom data-structure into
SQLite data-base by automatic creation of schema for the data-structure
Rajan
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