Data.GI.Base.Overloading

Helpers for dealing with overladed properties, signals and methods.

Type level inheritance

type family ParentTypes a :: [Type]

All the types that are ascendants of this type, including interfaces that the type implements.

Instances

type ParentTypes GError

There are no types in the bindings that a GError can be safely cast to.

Defined in Data.GI.Base.GError

type ParentTypes GError = '[] :: [Type]

type ParentTypes GValue

There are no types in the bindings that a GValue can be safely cast to.

Defined in Data.GI.Base.GValue

type ParentTypes GValue = '[] :: [Type]

type ParentTypes (GClosure a)

There are no types in the bindings that a closure can be safely cast to.

Defined in Data.GI.Base.GClosure

type ParentTypes (GClosure a) = '[] :: [Type]

class HasParentTypes (o :: Type)

A constraint on a type, to be fulfilled whenever it has a type instance for ParentTypes. This leads to nicer errors, thanks to the overlappable instance below.

Instances

HasParentTypes GError

Defined in Data.GI.Base.GError

HasParentTypes GValue

Defined in Data.GI.Base.GValue

(TypeError (('Text "Type \8216" ':<>: 'ShowType a) ':<>: 'Text "\8217 does not have any known parent types.") :: Constraint) => HasParentTypes a

Default instance, which will give rise to an error for types without an associated ParentTypes instance.

Defined in Data.GI.Base.Overloading

HasParentTypes (GClosure a)

Defined in Data.GI.Base.GClosure

type family IsDescendantOf (parent :: Type) (descendant :: Type) :: Constraint where ...

Check that a type is in the list of ParentTypes of another type.

Equations

IsDescendantOf d d = ()

IsDescendantOf p d = CheckForAncestorType d p (ParentTypes d)

asA :: (ManagedPtrNewtype a, ManagedPtrNewtype b, HasParentTypes b, IsDescendantOf a b) => b -> (ManagedPtr a -> a) -> a

Safe coercions to a parent class. For instance:

#show $ label `asA` Gtk.Widget

Looking up attributes in parent types

type family AttributeList a :: [(Symbol, Type)]

The list of attributes defined for a given type. Each element of the list is a tuple, with the first element of the tuple the name of the attribute, and the second the type encoding the information of the attribute. This type will be an instance of AttrInfo.

class HasAttributeList a

A constraint on a type, to be fulfilled whenever it has a type instance for AttributeList. This is here for nicer error reporting.

Instances

(TypeError (('Text "Type \8216" ':<>: 'ShowType a) ':<>: 'Text "\8217 does not have any known attributes.") :: Constraint) => HasAttributeList (a :: k)

Default instance, which will give rise to an error for types without an associated AttributeList.

Defined in Data.GI.Base.Overloading

type family ResolveAttribute (s :: Symbol) (o :: Type) :: Type where ...

Return the type encoding the attribute information for a given type and attribute.

Equations

ResolveAttribute s o = FindElement s (AttributeList o) (((('Text "Unknown attribute \8216" ':<>: 'Text s) ':<>: 'Text "\8217 for object \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

type family HasAttribute (attr :: Symbol) (o :: Type) :: Constraint where ...

A constraint imposing that the given object has the given attribute.

Equations

HasAttribute attr o = IsElem attr (AttributeList o) (() :: Constraint) (((('Text "Attribute \8216" ':<>: 'Text attr) ':<>: 'Text "\8217 not found for type \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

class HasAttr (attr :: Symbol) (o :: Type)

A constraint that enforces that the given type has a given attribute.

Instances

HasAttribute attr o => HasAttr attr o

Defined in Data.GI.Base.Overloading

Looking up signals in parent types

type family SignalList a :: [(Symbol, Type)]

The list of signals defined for a given type. Each element of the list is a tuple, with the first element of the tuple the name of the signal, and the second the type encoding the information of the signal. This type will be an instance of SignalInfo.

type family ResolveSignal (s :: Symbol) (o :: Type) :: Type where ...

Return the type encoding the signal information for a given type and signal.

Equations

ResolveSignal s o = FindElement s (SignalList o) (((('Text "Unknown signal \8216" ':<>: 'Text s) ':<>: 'Text "\8217 for object \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

type family HasSignal (s :: Symbol) (o :: Type) :: Constraint where ...

A constraint enforcing that the signal exists for the given object, or one of its ancestors.

Equations

HasSignal s o = IsElem s (SignalList o) (() :: Constraint) (((('Text "Signal \8216" ':<>: 'Text s) ':<>: 'Text "\8217 not found for type \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

Looking up methods in parent types

type family MethodResolutionFailed (method :: Symbol) (o :: Type) where ...

Returned when the method is not found, hopefully making the resulting error messages somewhat clearer.

Equations

MethodResolutionFailed m o = TypeError (((('Text "Unknown method \8216" ':<>: 'Text m) ':<>: 'Text "\8217 for type \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

type family UnsupportedMethodError (s :: Symbol) (o :: Type) :: Type where ...

A constraint that always fails with a type error, for documentation purposes.

Equations

UnsupportedMethodError s o = TypeError (((('Text "Unsupported method \8216" ':<>: 'Text s) ':<>: 'Text "\8217 for object \8216") ':<>: 'ShowType o) ':<>: 'Text "\8217.")

class OverloadedMethodInfo i o where

This is for debugging purposes, see resolveMethod below.

Methods

overloadedMethodInfo :: Maybe ResolvedSymbolInfo

class OverloadedMethod i o s where

Class for types containing the information about an overloaded method of type o -> s.

Methods

overloadedMethod

Arguments

:: o

-> s

The actual method being invoked.

data MethodProxy (info :: Type) (obj :: Type)

A proxy for carrying the types MethodInfoName needs (this is used for resolveMethod, see below).

Constructors

MethodProxy

data ResolvedSymbolInfo

Information about a fully resolved symbol, for debugging purposes.

Constructors

ResolvedSymbolInfo

Fields

• resolvedSymbolName :: Text
• resolvedSymbolURL :: Text

Instances

Show ResolvedSymbolInfo

Defined in Data.GI.Base.Overloading

Methods

showsPrec :: Int -> ResolvedSymbolInfo -> ShowS

show :: ResolvedSymbolInfo -> String

showList :: [ResolvedSymbolInfo] -> ShowS

resolveMethod :: forall info obj. OverloadedMethodInfo info obj => obj -> MethodProxy info obj -> Maybe ResolvedSymbolInfo

Return the fully qualified method name that a given overloaded method call resolves to (mostly useful for debugging).

resolveMethod widget #show