GdaParameter

GdaParameter — Represents a GValue with various attributes

Functions

Properties

gchar * entry-plugin Read / Write
GdaParameter * full-bind Read / Write
gulong g-type Read / Write / Construct Only
gboolean not-null Read / Write
gint restrict-column Read / Write
GdaDataModel * restrict-model Read / Write
GdaParameter * simple-bind Read / Write
gboolean use-default-value Read / Write

Signals

void restrict-changed Run First

Types and Values

Object Hierarchy

    GObject
    ╰── GdaObject
        ╰── GdaParameter

Implemented Interfaces

GdaParameter implements GdaReferer.

Description

A GdaParameter object basically is a specification for a value and can convey a value once one has been set.

The GdaParameter object offers other features such as:

  • keeping a list of objects which "are interested" (mentioned as "users" in the API) in the value placed in the parameter: this feature is usefull when parameters are created by objects and when these objects want to be reminded that the parameter has been created by them at a later time

  • aliasing (binding) to another parameter: this is an easy way to keep several parameters synchronized. There are two modes: one where parameters A and B will always have the same value and where parameter B will update itself whan A changes to mirror tha change but will be allowed to have its own changes afterwards.

  • values restrictions: a parameter can be told to choose a value among the values in a colmun in a GdaDataModel (beware that this is a declarative feature only and that no policy is enforced regarding values changes)

Functions

gda_parameter_new ()

GdaParameter *
gda_parameter_new (GType type);

Creates a new parameter of type type

Parameters

type

the GType requested

 

Returns

a new GdaParameter object


gda_parameter_new_copy ()

GdaParameter *
gda_parameter_new_copy (GdaParameter *orig);

Copy constructor.

Parameters

orig

a GdaParameter object to copy

 

Returns

a new GdaParameter object


gda_parameter_new_string ()

GdaParameter *
gda_parameter_new_string (const gchar *name,
                          const gchar *str);

Creates a new GdaParameter object of type G_TYPE_STRING

Parameters

name

the name of the parameter to create

 

str

the contents of the parameter to create

 

Returns

a new GdaParameter object


gda_parameter_new_boolean ()

GdaParameter *
gda_parameter_new_boolean (const gchar *name,
                           gboolean value);

Creates a new GdaParameter object of type G_TYPE_BOOLEAN

Parameters

name

the name of the parameter to create

 

value

the value to give to the new parameter

 

Returns

a new GdaParameter object


gda_parameter_get_g_type ()

GType
gda_parameter_get_g_type (GdaParameter *param);

Get the requested data type for param .

Parameters

param

a GdaParameter object

 

Returns

the data type


gda_parameter_get_value ()

const GValue *
gda_parameter_get_value (GdaParameter *param);

Get the value held into the parameter

Parameters

param

a GdaParameter object

 

Returns

the value (a NULL value returns a GDA_TYPE_NULL GValue)


gda_parameter_get_value_str ()

gchar *
gda_parameter_get_value_str (GdaParameter *param);

Get a string representation of the value stored in param . Calling gda_parameter_set_value_str() with this value will restore param 's current state.

Parameters

param

a GdaParameter object

 

Returns

a new string, or NULL if param 's value is NULL


gda_parameter_set_value ()

void
gda_parameter_set_value (GdaParameter *param,
                         const GValue *value);


gda_parameter_set_value_str ()

gboolean
gda_parameter_set_value_str (GdaParameter *param,
                             const gchar *value);

Same function as gda_parameter_set_value() except that the value is provided as a string, and may return FALSE if the string did not represent a correct value for the data type of the parameter.

Parameters

param

a GdaParameter object

 

value

a value to set the parameter to, as a string

 

Returns

TRUE if no error occurred


gda_parameter_declare_invalid ()

void
gda_parameter_declare_invalid (GdaParameter *param);

Forces a parameter to be invalid; to set it valid again, a new value must be assigned to it using gda_parameter_set_value().

Parameters

param

a GdaParameter object

 

gda_parameter_is_valid ()

gboolean
gda_parameter_is_valid (GdaParameter *param);

Get the validity of param (that is, of the value held by param )

Parameters

param

a GdaParameter object

 

Returns

TRUE if param 's value can safely be used


gda_parameter_get_default_value ()

const GValue *
gda_parameter_get_default_value (GdaParameter *param);

Get the default value held into the parameter. WARNING: the default value does not need to be of the same type as the one required by param .

Parameters

param

a GdaParameter object

 

Returns

the default value


gda_parameter_set_default_value ()

void
gda_parameter_set_default_value (GdaParameter *param,
                                 const GValue *value);


gda_parameter_get_exists_default_value ()

gboolean
gda_parameter_get_exists_default_value
                               (GdaParameter *param);

Parameters

param

a GdaParameter object

 

Returns

TRUE if param has a default value (which may be unspecified)


gda_parameter_set_exists_default_value ()

void
gda_parameter_set_exists_default_value
                               (GdaParameter *param,
                                gboolean default_value_exists);

Tells if param has default unspecified value. This function is usefull if one wants to inform that param has a default value but does not know what that default value actually is.


gda_parameter_set_not_null ()

void
gda_parameter_set_not_null (GdaParameter *param,
                            gboolean not_null);

Sets if the parameter can have a NULL value. If not_null is TRUE, then that won't be allowed

Parameters

param

a GdaParameter object

 

gda_parameter_get_not_null ()

gboolean
gda_parameter_get_not_null (GdaParameter *param);

Get wether the parameter can be NULL or not

Parameters

param

a GdaParameter object

 

Returns

TRUE if the parameter cannot be NULL


gda_parameter_restrict_values ()

gboolean
gda_parameter_restrict_values (GdaParameter *param,
                               GdaDataModel *model,
                               gint col,
                               GError **error);

Sets a limit on the possible values for the param parameter: the value must be among the values contained in the col column of the model data model.

Parameters

param

a GdaParameter object

 

model

a GdaDataModel object or NULL

 

col

the reference column in model

 

error

location to store error, or NULL

 

Returns

TRUE if no error occurred


gda_parameter_has_restrict_values ()

gboolean
gda_parameter_has_restrict_values (GdaParameter *param,
                                   GdaDataModel **model,
                                   gint *col);

Tells if param has its values restricted by a GdaDataModel, and optionally allows to fetch the restrictions.

Parameters

param

a GdaParameter

 

model

a place to store a pointer to the model restricting the parameter, or NULL.

 

col

a place to store the column in the model restricting the parameter, or NULL

 

Returns

TRUE if param has its values restricted.


gda_parameter_bind_to_param ()

void
gda_parameter_bind_to_param (GdaParameter *param,
                             GdaParameter *bind_to);

Sets param to change when bind_to changes (and does not make bind_to change when param changes)

Parameters

param

a GdaParameter

 

bind_to

a GdaParameter or NULL

 

gda_parameter_get_bind_param ()

GdaParameter *
gda_parameter_get_bind_param (GdaParameter *param);

Get the parameter which makes param change its value when the param's value is changed.

Parameters

param

a GdaParameter

 

Returns

the GdaParameter or NULL

Types and Values

GdaParameter

typedef struct _GdaParameter GdaParameter;

Property Details

The “entry-plugin” property

  “entry-plugin”             gchar *

Flags: Read / Write

Default value: NULL


The “full-bind” property

  “full-bind”                GdaParameter *

Flags: Read / Write


The “g-type” property

  “g-type”                   gulong

Flags: Read / Write / Construct Only


The “not-null” property

  “not-null”                 gboolean

Flags: Read / Write

Default value: FALSE


The “restrict-column” property

  “restrict-column”          gint

Flags: Read / Write

Allowed values: >= 0

Default value: 0


The “restrict-model” property

  “restrict-model”           GdaDataModel *

Flags: Read / Write


The “simple-bind” property

  “simple-bind”              GdaParameter *

Flags: Read / Write


The “use-default-value” property

  “use-default-value”        gboolean

Flags: Read / Write

Default value: FALSE

Signal Details

The “restrict-changed” signal

void
user_function (GdaParameter *gdaparameter,
               gpointer      user_data)

Parameters

gdaparameter

the object which received the signal.

 

user_data

user data set when the signal handler was connected.

 

Flags: Run First