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Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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Very First Steps to C-ORM

From: andrew cooke <andrew@...>

Date: Sat, 23 Feb 2013 17:24:45 -0300

I will post something mor epolished to the work blog eventually, but here 
is a quick example that I finally have working.

This example directory is included in the C-ORM sources.  This is the
contents after running configure for the package:

  > ls
  example_foo.c  example_foo.sh  foo.h  Makefile  Makefile.am  Makefile.in

And this is the struct that we want "ORM" for (in C):

  > cat foo.h
  #ifndef FOO_H
  #define FOO_H

  typedef struct foo {
    int id;
    int bar;
    char *baz;
  } foo;

  #endif

And this is the file used to populate the database:

  > cat example_foo.sh
  #!/bin/bash
  rm -f example_foo.db
  sqlite3 example_foo.db < foo.corm.sql
  sqlite3 example_foo.db <<EOF
  insert into foo (id,bar,baz) values (1,42,'towel');

(note that uses a file that doesn't exist yet - foo.corm.sql).

And this is the example program itself (again, including a file that does not
exist yet).

  > cat example_foo.c

  #include <stdio.h>

  #include "isti.h"
  #include "isti_flow.h"
  #include "isti_sql.h"
  #include "isti_sqlite.h"

  #include "foo.corm.h"

  ISTI_SQL_AS(sql)
  ISTI_SQLITE_AS(sqlite)
  CORM_FOO_AS(corm_foo)

  int main()
  {
    STATUS;

    // Obtain a connection to the database.  This uses an SQLite database, but
    // the handle returned is a generic API.

    isti_db *db = NULL;
    CHECK(sqlite.connect(&db, "example_foo.db", 60));

    // Construct a selector.  This does the work of extracting a value from the
    // database.

    corm_foo_select *s = NULL;
    CHECK(corm_foo.select(db, &s));

    // Call the selector, filtering the database entries, and extracting a
    // single instance of the `foo` struct.

    foo *f = NULL;
    CHECK(s->where(s)->bar(s, 42)->and(s)->\
	_bra(s)->baz(s, "towel")->or(s)->baz(s, "fish")->_ket(s)->\
	one(s, &f));
    printf("found foo instance with bar=%d and baz=%s\n", f->bar, f->baz);

    EXIT;

    if (f) free(f);
    if (s) status = corm_foo.free(s, status);
    if (db) status = db->close(db, status);

    if (status) fprintf(stderr, "error: %d\n", status);

    RETURN;
  }

Now, when I run make:

  > make
  PYTHONPATH=../../cgen/src python ../../cgen/src/isti/cgen/run.py foo.h
  gcc -std=gnu99 -DHAVE_CONFIG_H -I. -I../..   -I../../clib/src  -g -O0 -MT
  foo.corm.o -MD -MP -MF .deps/foo.corm.Tpo -c -o foo.corm.o foo.corm.c
  mv -f .deps/foo.corm.Tpo .deps/foo.corm.Po
  gcc -std=gnu99 -DHAVE_CONFIG_H -I. -I../..   -I../../clib/src  -g -O0 -MT
  example_foo.o -MD -MP -MF .deps/example_foo.Tpo -c -o example_foo.o
  example_foo.c
  mv -f .deps/example_foo.Tpo .deps/example_foo.Po
  /bin/bash ../../libtool --tag=CC   --mode=link gcc -std=gnu99  -g -O0
  -L../../clib/src/.libs -o example_foo foo.corm.o example_foo.o -lcorm
  -lsqlite3 
  libtool: link: gcc -std=gnu99 -g -O0 -o .libs/example_foo foo.corm.o
  example_foo.o  -L../../clib/src/.libs
  /home/andrew/project/c-orm/hg/clib/src/.libs/libcorm.so
  /usr/lib/x86_64-linux-gnu/libsqlite3.so
  ./example_foo.sh

    to run the example from the example/src directory:
      LD_LIBRARY_PATH=../../clib/src/.libs ./example_foo

And let's follow the instructions:

  > LD_LIBRARY_PATH=../../clib/src/.libs ./example_foo
  select id,bar,baz from foo where bar=? and ( baz=? or baz=? )
  found foo instance with bar=42 and baz=towel

Yay!

Andrew

Updated Syntax

From: andrew cooke <andrew@...>

Date: Sun, 24 Feb 2013 02:01:53 -0300

I've changed the syntax for restricting queries.  As a consequence you have
several options:

This is verbose, but parameters are strongly typed and the compiler can detect
spelling mistakes.  "bra" and "ket" are particularly kludgy.

  s->_where(s)->bar(s, "=", 42)->_and(s)->\
  _bra(s)->baz(s, "like", "towel")->_or(s)->baz(s, "like", "fish")->_ket(s)->\
  _one(s, &f)

This is equivalentm, but much more compact and with much less checking:

  s->_(s ,"where bar=%d and (baz like %s or baz like %s)", 42, "towel", "fish")->\
  _one(s, &f)

For simple queries, the verbose approach has implicit "and":

  s->bar(s, "=", 42)->baz(s, "like", "towel")->_one(s, &f)

Literals are allowed anywhere:

  s->_(s, "where")->bar(s, "=", 42)->baz(s, "like", "towel")->\
  _(s, "limit 1")->_one(s, &f)

Andrew

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