|  |  |  | GNOME Data Access manual |  | 
|---|---|---|---|---|
            GdaParameter;
GdaParameter* gda_parameter_new             (GType type);
GdaParameter* gda_parameter_new_copy        (GdaParameter *orig);
GdaParameter* gda_parameter_new_string      (const gchar *name,
                                             const gchar *str);
GdaParameter* gda_parameter_new_boolean     (const gchar *name,
                                             gboolean value);
GType       gda_parameter_get_g_type        (GdaParameter *param);
void        gda_parameter_declare_param_user
                                            (GdaParameter *param,
                                             GdaObject *user);
GSList*     gda_parameter_get_param_users   (GdaParameter *param);
const GValue* gda_parameter_get_value       (GdaParameter *param);
gchar*      gda_parameter_get_value_str     (GdaParameter *param);
void        gda_parameter_set_value         (GdaParameter *param,
                                             const GValue *value);
gboolean    gda_parameter_set_value_str     (GdaParameter *param,
                                             const gchar *value);
void        gda_parameter_declare_invalid   (GdaParameter *param);
gboolean    gda_parameter_is_valid          (GdaParameter *param);
const GValue* gda_parameter_get_default_value
                                            (GdaParameter *param);
void        gda_parameter_set_default_value (GdaParameter *param,
                                             const GValue *value);
gboolean    gda_parameter_get_exists_default_value
                                            (GdaParameter *param);
void        gda_parameter_set_exists_default_value
                                            (GdaParameter *param,
                                             gboolean default_value_exists);
void        gda_parameter_set_not_null      (GdaParameter *param,
                                             gboolean not_null);
gboolean    gda_parameter_get_not_null      (GdaParameter *param);
gboolean    gda_parameter_restrict_values   (GdaParameter *param,
                                             GdaDataModel *model,
                                             gint col,
                                             GError **error);
gboolean    gda_parameter_has_restrict_values
                                            (GdaParameter *param,
                                             GdaDataModel **model,
                                             gint *col);
void        gda_parameter_replace_param_users
                                            (GdaParameter *param,
                                             GHashTable *replacements);
void        gda_parameter_bind_to_param     (GdaParameter *param,
                                             GdaParameter *bind_to);
GdaParameter* gda_parameter_get_bind_param  (GdaParameter *param);
"entry-plugin" gchararray : Read / Write "full-bind" GdaParameter : Read / Write "g-type" gulong : Read / Write / Construct Only "not-null" gboolean : Read / Write "restrict-column" gint : Read / Write "restrict-model" GdaDataModel : Read / Write "simple-bind" GdaParameter : Read / Write "use-default-value" gboolean : Read / Write
"restrict-changed" void user_function (GdaParameter *gdaparameter, gpointer user_data) : Run first
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)
GdaParameter* gda_parameter_new (GType type);
Creates a new parameter of type type
| type: | the GType requested | 
| Returns : | a new GdaParameter object | 
GdaParameter* gda_parameter_new_copy (GdaParameter *orig);
Copy constructor.
| orig: | a GdaParameter object to copy | 
| Returns : | a new GdaParameter object | 
GdaParameter* gda_parameter_new_string (const gchar *name, const gchar *str);
Creates a new GdaParameter object of type G_TYPE_STRING
| name: | the name of the parameter to create | 
| str: | the contents of the parameter to create | 
| Returns : | a new GdaParameter object | 
GdaParameter* gda_parameter_new_boolean (const gchar *name, gboolean value);
Creates a new GdaParameter object of type G_TYPE_BOOLEAN
| name: | the name of the parameter to create | 
| value: | the value to give to the new parameter | 
| Returns : | a new GdaParameter object | 
GType gda_parameter_get_g_type (GdaParameter *param);
Get the requested data type for param.
| param: | a GdaParameter object | 
| Returns : | the data type | 
void        gda_parameter_declare_param_user
                                            (GdaParameter *param,
                                             GdaObject *user);
Tells that user is potentially using param.
| param: | a GdaParameter object | 
| user: | the GdaObject object using that parameter for | 
GSList* gda_parameter_get_param_users (GdaParameter *param);
Get the GdaEntityField objects which created param (and which will use its value)
| param: | a GdaParameter object | 
| Returns : | the list of GdaEntityField object; it must not be changed or free'd | 
const GValue* gda_parameter_get_value (GdaParameter *param);
Get the value held into the parameter
| param: | a GdaParameter object | 
| Returns : | the value (a NULL value returns a GDA_TYPE_NULL GValue) | 
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.
| param: | a GdaParameter object | 
| Returns : | a new string, or NULLifparam's value is NULL | 
void gda_parameter_set_value (GdaParameter *param, const GValue *value);
| param: | |
| value: | 
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.
| param: | a GdaParameter object | 
| value: | a value to set the parameter to, as a string | 
| Returns : | TRUE if no error occurred | 
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().
| param: | a GdaParameter object | 
gboolean gda_parameter_is_valid (GdaParameter *param);
Get the validity of param (that is, of the value held by param)
| param: | a GdaParameter object | 
| Returns : | TRUE if param's value can safely be used | 
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.
| param: | a GdaParameter object | 
| Returns : | the default value | 
void gda_parameter_set_default_value (GdaParameter *param, const GValue *value);
| param: | |
| value: | 
gboolean    gda_parameter_get_exists_default_value
                                            (GdaParameter *param);
| param: | a GdaParameter object | 
| Returns : | TRUE if paramhas a default value (which may be unspecified) | 
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.
| param: | |
| default_value_exists: | 
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
| param: | a GdaParameter object | 
| not_null: | 
gboolean gda_parameter_get_not_null (GdaParameter *param);
Get wether the parameter can be NULL or not
| param: | a GdaParameter object | 
| Returns : | TRUE if the parameter cannot be NULL | 
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.
| 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 | 
gboolean    gda_parameter_has_restrict_values
                                            (GdaParameter *param,
                                             GdaDataModel **model,
                                             gint *col);
Tells if param has its values restricted by a GdaDataModel, and optionnaly
allows to fetch the resteictions.
| 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 paramhas its values restricted. | 
void        gda_parameter_replace_param_users
                                            (GdaParameter *param,
                                             GHashTable *replacements);
For each declared parameter user in the replacements keys, declare the value stored in
replacements also as a user of param.
| param: | a GdaParameter object | 
| replacements: | the (objects to be replaced, replacing object) pairs | 
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)
| param: | a GdaParameter | 
| bind_to: | a GdaParameter or NULL | 
GdaParameter* gda_parameter_get_bind_param (GdaParameter *param);
Get the parameter which makes param change its value when the param's value is changed.
| param: | a GdaParameter | 
| Returns : | the GdaParameter or NULL | 
restrict-column" property"restrict-column" gint : Read / Write
Allowed values: >= 0
Default value: 0
void user_function (GdaParameter *gdaparameter, gpointer user_data) : Run first
| gdaparameter: | the object which received the signal. | 
| user_data: | user data set when the signal handler was connected. |