Re: [Cppcms-users] Continued discussion on bug 3536452 - transaction in progress

[Artyom B. <art...@ya...>]

I think it would be better to create some kind of generic guard class with
different commits/rollbacks:


// information about statements

class guard {
   guard();

   guard(std::string const &on_start)

   guard(std::string const &on_start,
         std::string const &on_commit);

   guard(std::string const &on_start,
         std::string const &on_commit,
         std::string const &on_rollback);

   // set explicitly

   void on_start(std::string const &);     // default begin

   void on_commit(std::string const &);    // default commit

   void on_rollback(std::string const &);  // default rollback;


};


Now out transaction constructors would look like:

   // ordinary transaction

   transaction(cppdb::session &sql);
   // custom transaction

   transaction(cppdb::session &sql,guard const &g);


Now when I can run stuff like

   cppdb::guard myguard("BEGIN IMMEDIATE");


   cppdb::scope tr(sql,myguard);
   ...

   tr.commit();

or use it with savepoints or nested transactions



Define guard


   cppdb::guard myguard(
        "SAVEPOINT temp",
        "ROLLBACK TO SAVEPOINT temp",
        "RELEASE SAVEPOINT temp");

  or more explicitlu


   cppdb::guard myguard;

   myguard.on_start("SAVEPOINT temp");
   myguard.on_commit("RELEASE SAVEPOINT temp");
   myguard.on_rollback("ROLLBACK TO SAVEPOINT temp");


And now do stuff like:

   cppdb::transaction tr(sql);
         for(...) {
             cppdb::transaction sp(sql,myguard);
             ...
             sp.commit();

         }
       

   tr.commit();


This would be much more complete interface.




 
Artyom Beilis
--------------
CppCMS - C++ Web Framework:   http://cppcms.com/
CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/



----- Original Message -----
> From: "ele...@ex..." <ele...@ex...>

> 
> Here is another idea.
> 
> 1) Create a cppdb::base_transaction class and implement the current
> cppdb::transaction in it, but without calling begin() in it's constructor.
> 
> Make its functions/destructor virtual if users want to overload & support
> polymorphism.
> 
> 2) Make cppdb::transaction inherit from base_transaction and call
> session::begin() in it's constructor, so that current behavior is kept and
> there wont be any API breakage.
> 
> 3) Users will then be able to inherit from cppdb::base_transaction and
> create their own transaction classes.
> 
> This should avoid adding a default constructor and possibly confuse users.
> 
> Is this a solid proposal Artyom?
> 
> 
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