Tango::DbDatum Class Reference

A database value. More...

#include "tango.h"

Public Member Functions
Constructors
	DbDatum (string name)
	Create a DbDatum object. More...
	DbDatum (const char *name)
	Create a DbDatum object. More...
Operators overloading
void	operator<< (bool val)
	Inserters operators. More...
bool	operator>> (bool &val)
	Extractors operators. More...
Exception related methods methods
void	exceptions (bitset< DbDatum::numFlags > fl)
	Set exception flag. More...
bitset< DbDatum::numFlags >	exceptions ()
	Get exception flag. More...
void	reset_exceptions (except_flags fl)
	Reset one exception flag. More...
void	set_exceptions (except_flags fl)
	Set one exception flag. More...
Miscellaneous methods
bool	is_empty ()
	Test if instance is empty. More...

Detailed Description

A database value.

A single database value which has a name, type, address and value and methods for inserting and extracting C++ native types. This is the fundamental type for specifying database properties. Every property has a name and has one or more values associated with it. The values can be inserted and extracted using the operators << and >> respectively. A status flag indicates if there is data in the DbDatum object or not. An additional flag allows the user to activate exceptions.

Constructor & Destructor Documentation

DbDatum() [1/2]

Tango::DbDatum::DbDatum

(

string

name

)

Create a DbDatum object.

Create an instance of the DbDatum class with name set to the specified parameter

Parameters

[in]

name

The CORBA ORB pointer. Default value is fine for 99 % of cases

DbDatum() [2/2]

Tango::DbDatum::DbDatum

(

const char *

name

)

Create a DbDatum object.

Create an instance of the DbDatum class with name set to the specified parameter

Parameters

[in]

name

The CORBA ORB pointer. Default value is fine for 99 % of cases

Member Function Documentation

exceptions() [1/2]

bitset<DbDatum::numFlags> Tango::DbDatum::exceptions ( )

inline

Get exception flag.

Returns the whole exception flags. The following is an example of how to use these exceptions related methods

DbDatum da;
 
bitset<DbDatum::numFlags> bs = da.exceptions();
cout << "bs = " << bs << endl;
 
da.set_exceptions(DbDatum::wrongtype_flag);
bs = da.exceptions();
 
cout << "bs = " << bs << endl;

Returns

The exception flag

exceptions() [2/2]

void Tango::DbDatum::exceptions ( bitset< DbDatum::numFlags >  fl )

inline

Set exception flag.

Is a method which allows the user to switch on/off exception throwing for trying to extract data from an empty DbDatum object. The default is to not throw exception. The following flags are supported :

• isempty_flag - throw a WrongData exception (reason = API_EmptyDbDatum) if user tries to extract data from an empty DbDatum object
• wrongtype_flag - throw a WrongData exception (reason = API_IncompatibleArgumentType) if user tries to extract data with a type different than the type used for insertion

Parameters

[in]

fl

The exception flag

is_empty()

bool Tango::DbDatum::is_empty

(

)

Test if instance is empty.

is_empty() is a boolean method which returns true or false depending on whether the DbDatum object contains data or not. It can be used to test whether a property is defined in the database or not e.g.

sl_props.push_back(parity_prop);
dbase->get_device_property(device_name, sl_props);
 
if (! parity_prop.is_empty())
{
    parity_prop >> parity;
}
else
{
    cout << device_name << " has no parity defined in database !" << endl;
}

Returns

True if DdDatum instance is empty

Exceptions

WrongData

if requested

operator<<()

void Tango::DbDatum::operator<<

(

bool

val

)

Inserters operators.

The insert and extract operators are specified for the following C++ types :

• bool
• unsigned char
• short
• unsigned short
• DevLong
• DevULong
• DevLong64
• DevULong64
• float
• double
• string
• char* (insert only)
• const char *
• vector<string>
• vector<short>
• vector<unsigned short>
• vector<DevLong>
• vector<DevULong>
• vector<DevLong64>
• vector<DevULong64>
• vector<float>
• vector<double>

Here is an example of creating, inserting and extracting some DbDatum types :

DbDatum my_short("my_short"), my_long(“my_long”), my_string("my_string");
DbDatum my_float_vector("my_float_vector"), my_double_vector("my_double_vector");
 
string a_string;
short a_short;
DevLong a_long;
vector<float> a_float_vector;
vector<double> a_double_vector;
 
my_short << 100; // insert a short
my_short >> a_short; // extract a short
my_long << 1000; // insert a DevLong
my_long >> a_long; // extract a long
my_string << string("estas lista a bailar el tango ?"); // insert a string
my_string >> a_string; // extract a string
my_float_vector << a_float_vector // insert a vector of floats
my_float_vector >> a_float_vector; // extract a vector of floats
my_double_vector << a_double_vector; // insert a vector of doubles
my_double_vector >> a_double_vector; // extract a vector of doubles

Parameters

[in]

val

Data to be inserted

Exceptions

WrongData

if requested

operator>>()

bool Tango::DbDatum::operator>>

(

bool &

val

)

Extractors operators.

See documentation of the DbDatum::operator<< for details

Parameters

[out]

val

Data to be initalized with database value

Returns

A boolean set to true if the extraction succeeds

Exceptions

WrongData

if requested

reset_exceptions()

void Tango::DbDatum::reset_exceptions ( except_flags  fl )

inline

Reset one exception flag.

Resets one exception flag

Parameters

[in]

fl

The exception flag

set_exceptions()

void Tango::DbDatum::set_exceptions ( except_flags  fl )

inline

Set one exception flag.

Sets one exception flag. See DbDatum::exceptions() for a usage example

Parameters

[in]

fl

The exception flag

---

The documentation for this class was generated from the following file:

• dbapi.h