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Patches for any of these thoughtfully considered! See the HACKERS.txt
file for instructions on sending patches.
Any Version
-----------
o Any time you must hand-roll some SQL code in your program,
consider whether it could be generalized to a widely-useful
API feature.
o Suppress DOS line-ending related diffs from examples/cgi_jpeg
output when running dtest on Windows. Check for -D?
o Need to link statically to connect to MySQL Embedded?
http://stackoverflow.com/questions/672451/howto-communicate-with-mysql-embedded-server-from-mysql-dll
o When Bakefile allows, bring examples/vstudio/* into the top-level
build system. This will let us generate separate project
files for each VC++ version we support, let us use MYSQL_WIN_DIR
variable instead of hard-coded paths, and build against the local
version of MySQL++ instead of requiring it to be installed first.
Should probably drop the MFC example project, to avoid requiring
Visual C++ Professional.
o Query::storein(slist<T>&) is unusable. As a template method, it
must be defined in a header file; we cannot #include config.h from
a header, thus the proper HAVE macro that would let us define this
template method is never defined.
One solution is to create lib/slist.h.in, parameterized by the
detected slist type name and the header file defining it. This
will #include the proper header file, define SList<T>::Type (a
template typdedef: http://www.gotw.ca/gotw/079.htm), and #define
MYSQLPP_HAVE_SLIST. Then Query::storein() can be wrapped by an
ifdef checking for MYSQLPP_HAVE_SLIST, only defined when the
configure script found a suitable slist type.
Also create a default lib/slist.h file, checked into svn as
lib/slistdef.h and copied to slist.h on tarball creation. Remove
this file early in configure script run, so we're forced to
overwrite its contents with detected values. Default version
contains ifdefs for non-autoconf platforms where we know what
slist definition is available on that platform. Xcode, for
instance, will let us use <ext/slist>.
v3.2 Plan: Finish SSQLS v2
--------------------------
See http://lists.mysql.com/plusplus/6929 for high-level plan.
o Goal: Restore VC++ 2003 compatibility with SSQLS, lost with v1
o C++ code generator, from walking DSL parse tree:
examples/stock.ssqls gives ssqls_stock.h containing:
class SQLStock : public mysqlpp::SsqlsBase
{
public:
SQLStock(Connection* conn = 0); // default ctor
SQLStock(const SQLStock& other);
SQLStock(const mysqlpp::Row& row,
Connection* conn = 0); // full init from query
SQLStock(mysqlpp::sql_bigint key1); // exemplar creation
SQLStock(Connection* conn,
mysqlpp::sql_bigint key1) // calls load();
SQLStock(
mysqlpp::sql_bigint f1,
mysqlpp::sql_bigint f2,
mysqlpp::sql_double f3,
mysqlpp::sql_double f4,
const mysqlpp::sql_date& f5,
const mysqlpp::sql_mediumtext& f6); // full init
SQLStock(Connection* conn,
mysqlpp::sql_bigint f2,
mysqlpp::sql_double f3,
mysqlpp::sql_double f4,
const mysqlpp::sql_date& f5,
const mysqlpp::sql_mediumtext& f6); // calls create()
SQLStock(Connection* conn,
mysqlpp::sql_bigint f1,
mysqlpp::sql_bigint f2,
mysqlpp::sql_double f3,
mysqlpp::sql_double f4,
const mysqlpp::sql_date& f5,
const mysqlpp::sql_mediumtext& f6); // calls save()
bool createTable(Connection* conn = 0) const;
const char* getTableName() const
{ return class_table_name_ || table(); }
void setTableName(const char* name)
{ instance_table(name); }
static void setTableName(const char* name)
{ class_table_name_ = name; }
std::ostream& equal_list(std::ostream& os) const;
std::ostream& json(std::ostream& os) const;
std::ostream& name_list(std::ostream& os) const;
std::ostream& value_list(std::ostream& os) const;
std::ostream& xml(std::ostream& os) const;
mysqlpp::sql_bigint getId() const;
mysqlpp::sql_bigint getNum() const;
mysqlpp::sql_double getWeight() const;
mysqlpp::sql_double getPrice() const;
const mysqlpp::sql_date& getSdate() const;
const mysqlpp::sql_mediumtext& getDescription() const;
void setId(mysqlpp::sql_bigint value);
void setNum(mysqlpp::sql_bigint value);
void setWeight(mysqlpp::sql_double value);
void setPrice(mysqlpp::sql_double value);
void setSdate(const mysqlpp::sql_date& value);
void setDescripion(const mysqlpp::sql_mediumtext& value);
bool operator<(const SQLStock& rhs) const;
SQLStock& operator=(const SQLStock& rhs);
protected:
mysqlpp::sql_bigint id_;
mysqlpp::sql_bigint num_;
mysqlpp::sql_double weight_;
mysqlpp::sql_double price_;
mysqlpp::sql_date sdate_;
mysqlpp::sql_mediumtext description_;
std::bitset<6> set_fields_;
private:
static const char* class_table_name_;
};
...and ssqls_stock.cc, containing implementation for same.
o Ensure we're using case-insensitive SQL column to C++ field name
matching. Column names aren't case-sensitive in SQL.
o SQL table updater/builder, -T option, taking .ssqls and
creating or updating the DB table to match.
o If using accessors, generate "std::bitset<num_fields> is_set_",
and set the appropriate bit when calling each setFoo() so we
can intuit which fields were set. Probably also need an enum:
enum FieldIndices {
id_field_index_,
num_field_index_,
...
};
This will allow Query::select(), for instance, to figure out that
we want it to select by a non-key field, returning all matches.
o Define operator<< for SSQLS and a set of manipulators which
govern whether the operator calls equal_list(), json(),
name_list(), value_list(), or xml() to do the actual insertion.
o Define operator<< for sequence_container<SsqlsBase> and similar
for associative containers. Give mysql(1)-like ASCII grid or
some other table format.
o Define operator>> for SSQLS, taking XML as input, in the form
emitted via xml(). expat uses the new BSD license, so maybe
we can just drop it in the tree, with an option to use the
platform expat on autoconf systems.
o MySQL table metadata to SSQLSv2 data structure translator.
(-s, -u, -p and -t flag support.) Add this to dtest, extracting
stock.ssqls definition from DB.
o Replace Query's template methods taking SSQLSes with concrete
methods taking const SsqlsBase&.
o Create Query::remove(const SsqlsBase&)
o Try to remove of 'explicit' from Date, DateTime and Time
ctors taking stringish types. (Can't do it for real until v4,
but we can lay the ground work here.)
o Auto-create() ctor: if there is an auto_increment field,
populate it on query success.
o Detect ctor conflicts corresponding to sql_create_N(N, N...)
in SSQLSv1. ssqlsxlat can be smart enough to just not emit
duplicate ctors.
o Special case of ctor suppression: if the number of key fields
equals the total number of fields, you get an auto-load() ctor,
not auto-update().
o Replace CREATE TABLE SQL in resetdb with create_table() calls.
o Option to use integer indices into Row when populating? Only
bother if it gives a speed advantage we can actually see,
because it removes all the dynamic typing advantages we got
with the change to field name indices in v3.0.
o Try to add Query::storein(container, ssqls), which generates
SELECT * from {ssqls.table()} and stores the result. May not be
possible due to existing overloads, but try. If it works, use
this form in the userman Overview section, saving one LOC.
o Convert SSQLS v1 examples to v2. SSQLS v2 isn't done until
there's a straightformward conversion path for all examples.
o Add #warning to generated ssqls.h saying that you should now use
SSQLS v2. Wrap it in a check for MYSQLPP_ALLOW_SSQLS_V1,
so people can disable the warning.
v3.3 Tentative Plan
-------------------
o Add Query::storein<Container, T>(container), getting table
name from container::value_type.table() instead.
o Define operator<< for Fields, Row, StoreQueryResult, etc., giving
CSV format.
o Remove libexcommon. Between above and SSQLSv2, we should have
everything we need to get equivalent output without special
purpose code. There should be no ad hoc data dumping code in
the examples.
o Bring back mandatory quoting for manipulators? If someone says
os << mysqlpp::escape << foo; do they not really really mean
escape foo? Automatic quoting and escaping is different. See
http://lists.mysql.com/plusplus/7999
o Configure script should try to get MySQL C API directories
from mysql_config.
o If pkg-config is available, register ourselves with it using
information discovered by configure. Also, write out a
mysql++-config script, which either wraps pkg-config or
reinvents it, poorly, for systems that don't have it.
o Add String::operator==(const mysqlpp::null_type&). Needed to
allow comparison of row[x] returns to SQL null. Change one of
the examples to show it?
o Memory "leak" and C API library init fixes:
- Add DBDriver::library_begin() and library_end(), wrapping
similarly named functions in the C API.
- Create Process class, which you create at the top of main()
on the stack, purely to call these automatically.
- Update userman to recommend creating Process object in
ConnectionPool derivatives, instead.
- Create Thread class to call existing DBDriver::thread_start()
and thread_end(), similar to Process, created on the stack
of the thread entry function.
- Move memory leak FAQ into userman, rewriting it to cover
all this.
o mysqlpp::execute manipulator. Immediately executes built
query string. Works best with exceptions, as that's the only way
to detect failures.
o Chris Frey's packarray class
o Create adaptors for std::bitset, for storing binary data in a
MySQL table. Make two options available, one for storing the
return from bitset::to_ulong() in an UNSIGNED INTEGER column,
and another for storing a larger set of bits in a more flexible
way, perhaps as a BLOB.
o Create a backtick manipulator for use by field_list() in row.h
and ssqls.h. These currently use do_nothing0, but that prevents
use of SQL reserved words as identifiers.
o Has experience with new thread awareness changed our mind on
atomic inc/dec of reference counts in RefCounted*?
o Create a fixed-point data type for use with SQL's DECIMAL and
related types. Right now, sql_decimal is a typedef for double,
so you lose accuracy in the fractional part. Don't forget to
include an "is_null" flag to cope with conversion from infinite
or NaN float values; that's how MySQL stores these.
o Optional checked conversions in String for numerics: throw
BadConversion on range overflow?
o Add Query::storein_if(), mirroring store_if()
o Add a method to mysqlpp::String to return a widened version of the
string. Probably make return type templatized so we can return
wstring, C++/CLI native strings, etc. Then convert examples that
do this conversion to use this new mechanism.
o Try to add operator std::string to String. If it doesn't work,
explain why not in the userman, and in Row::operator[] refman.
o Wrap LOAD DATA INFILE:
bool Query::load_file(
const char* path,
bool local_path,
const char* table,
const char* field_terminator = 0, // default \t
const char* field_encloser = 0, // default none
const char* field_escape = 0, // default \
const char* line_terminator = 0, // \n on *ix, \r\n on Windows
const char* line_starter = 0, // default none
const char* character_set = 0, // default UTF-8
const char* comment_prefix = 0, // ignore no lines
bool replace_existing = false,
bool ignore_duplicates = false,
bool low_priority = false,
int skip_lines = 0);
o Wrappers for above: load_local_tab_file(), load_local_csv_file(),
load_remote_*()...
o Query::save_file() interfaces, wrapping SELECT ... INTO FILE,
modeled on above.
v4.0 or Later
-------------
o Database independence:
- Use libdbi or similar? http://libdbi.sf.net/
- Make DBDriver class purely abstract; move its entire functional
contents to new MysqlDriver.
- Must create at least two other DBDriver subclasses to
ensure base class is reusable before releasing v4.0.
PostgresDriver and SqlLiteDriver?
- Templatize all classes that use DBDriver interface with the
DB driver type. This lets you specify the driver type to use
with a Connection and all its children without modifying the
existing method parameter lists. This also lets us worry less
about C API types, as they can be hidden away behind typedefs:
class MysqlDriver : public DBDriver { ...
typedef MYSQL_ROW row_type;
...
}
template <class DBD = MysqlDriver>
class Connection ... { ...
Query<DBD> query();
...
}
template <class DBD = MysqlDriver>
class UseQueryResult { ...
DBD::row_type fetch_raw_row();
}
- Tricky bits:
- Initializing result set objects.
- type_info module. Extremely closely tied to MySQL C API
right now. Will probably have to turn it into a parallel
class hierarchy to DBDriver, or fold it in with same.
- Building MySQL++ on systems without autoconf. How to
specify what DB engines are available? Probably default to
supporting MySQL only, and let people turn things on manually
as they need them. Or, maybe make them use Bakefile so they
can fiddle with the options if they want something atypical.
o Fork mysqlpp::String into mysqlpp::Blob, which differs only in
that it knows that it should be automatically quoted and escaped
when inserted into a SQL query. Could do this in 3.x, but it's a
pretty serious API breakage.
o Some sort of support for prepared statements. Can we hijack
the template query mechanism?
o If SSQLSv2 does use a common base class, change Query template
methods taking SSQLS into concrete methods taking SsqlsBase&.
o Make Query::insert(), replace() and update() execute their
queries immediately. Requires an ABI break, because they'll
have to return SimpleResult.
o Switch Query's safe bool to overload basic_ios<>::operator
void*() instead. We create an ambiguous conversion in bool
context with some C++ standard libraries otherwise.
o Templatize mysqlpp::String on value_type so it can be used to
hold wide characters. Then the method that converts UTF-8 to the
platform's best wide character type can just return a different
variant of mysqlpp::String.
o Add wrapper functions to Null<> like length() that call the
corresponding function on data member, if present, to make it
more transparent. At minimum, mirror the std::string API.
o Transaction class should check an "in transaction" flag on
Connection (or DBDriver) before sending BEGIN, defaulting to
false. If set, the Transaction object does nothing. If not
set, set it and send the query. This prevents it from trying
to set up nested queries, which MySQL doesn't support.
o Remove throw-spec for std::out_of_range from SQLTypeAdapter::at().
It no longer throws this, and throw-specs are passee' anyway.
o Store failed query string in BadQuery exception object, to make
logging and debugging easier. One could have a try block wrapping
many queries, and be able to recover the failed query string from
the exception object, instead of somehow keeping track yourself.
Patch: http://lists.mysql.com/plusplus/8374
o Query and SQLStream could have a common base class that would
allow the stream manipulator functions to catch and modify
strings based on only one dynamic_cast instead of requiring
two as it does since the addition of the SQLStream class.
o Make internal call chain steps like Query::execute(SQLQueryParms&)
protected? No good reason for end users to call it, and making
it part of the public API causes people to try calling it, and
discovering that it's not a very elegant interface, compared to
the ones taking SQLStrings.
o SQL time type allows +/- 839 hours of range. v3.0 code doesn't
cope with negative times, and if we change it to use signed
integers, we'll still only get +/-127 hours instead of +255.
Need to switch the hour field to a short to get the full range.
o Create a thread-safe message queue for separating DB access and
data use into multiple threads. Something like ConnectionPool,
optional and with no ties to the internals of MySQL++. There
could be an adapter between one end of the queue and a Connection
object, which creates Queries to handle standardized messages,
delivering the results back to the queue.
o Get rid of two-step create in DBDriver, requiring a connection to
be established in ctor for object to be valid? RAII. The
DB-specific functions that don't require a connection can be
static methods. Tricky bit: a failed Connection::connect() call
will likely be followed by an indirect call to DBDriver::err*().
Does Connection cache the error value and message? If we can pull
this off, we can drop the DBDriver::is_connected_ flag and change
Connection::connected() to "return driver_ != 0".
o Add STL-like custom Allocator template parameters to memory-hungry
classes like Row? Useful in apps that process lots of data over
long periods, causing heap fragmentation with the default C++
allocator.
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