Struct mz_sql::session::vars::SystemVar

pub struct SystemVar {
    definition: VarDefinition,
    persisted_value: Option<Box<dyn Value>>,
    dynamic_default: Option<Box<dyn Value>>,
}

A SystemVar is persisted on disk value for a configuration parameter. If unset, the server default is used instead.

Fields

definition: VarDefinition

persisted_value: Option<Box<dyn Value>>

Value currently persisted to disk.

dynamic_default: Option<Box<dyn Value>>

Current default, not persisted to disk.

Implementations

impl SystemVar

pub fn new(definition: VarDefinition) -> Self

fn is_default(&self, input: VarInput<'_>) -> Result<bool, VarError>

pub fn value_dyn(&self) -> &dyn Value

pub fn value<V: 'static>(&self) -> &V

fn parse(&self, input: VarInput<'_>) -> Result<Box<dyn Value>, VarError>

fn set(&mut self, input: VarInput<'_>) -> Result<bool, VarError>

fn reset(&mut self) -> bool

fn set_default(&mut self, input: VarInput<'_>) -> Result<(), VarError>

fn validate_constraints(&self, val: &dyn Value) -> Result<(), VarError>

Trait Implementations

impl Clone for SystemVar

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SystemVar

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Var for SystemVar

fn name(&self) -> &'static str

Returns the name of the configuration parameter.

fn value(&self) -> String

Constructs a flattened string representation of the current value of the configuration parameter.

fn description(&self) -> &'static str

Returns a short sentence describing the purpose of the configuration parameter.

fn type_name(&self) -> Cow<'static, str>

Returns the name of the type of this variable.

fn visible( &self, user: &User, system_vars: Option<&SystemVars>, ) -> Result<(), VarError>

Indicates wither the Var is visible as a function of the user and system_vars. “Invisible” parameters return VarErrors.

fn as_var(&self) -> &dyn Var

where Self: Sized,

Upcast self to a dyn Var, useful when working with multiple different implementors of Var.