 | glib-0.11.2: Binding to the GLIB library for Gtk2Hs. | Source code | Contents | Index |
| System.Glib.Attributes |
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| Contents |
Attributes interface
Attributes of an object can be get and set. Getting the value of an object's attribute is straingtforward. As an example consider a button widget and an attribute called buttonLabel.
value <- get button buttonLabel
The syntax for setting or updating an attribute is only slightly more complex. At the simplest level it is just:
set button [ buttonLabel := value ]
However as the list notation would indicate, you can set or update multiple attributes of the same object in one go:
set button [ buttonLabel := value, buttonFocusOnClick := False ]
You are not limited to setting the value of an attribute, you can also apply an update function to an attribute's value. That is the function receives the current value of the attribute and returns the new value.
set spinButton [ spinButtonValue :~ (+1) ]
There are other variants of these operators, (see AttrOp). ':=>' and ':~>' and like ':=' and ':~' but operate in the IO monad rather than being pure. There is also '::=' and '::~' which take the object as an extra parameter.
Attributes can be read only, write only or both read/write.
| type Attr o a = ReadWriteAttr o a a | ||||||||
| type ReadAttr o a = ReadWriteAttr o a () | ||||||||
| type WriteAttr o b = ReadWriteAttr o () b | ||||||||
| data ReadWriteAttr o a b | ||||||||
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| get :: o -> ReadWriteAttr o a b -> IO a | ||||||||
| set :: o -> [AttrOp o] -> IO () | ||||||||
| newNamedAttr :: String -> (o -> IO a) -> (o -> b -> IO ()) -> ReadWriteAttr o a b | ||||||||
| readNamedAttr :: String -> (o -> IO a) -> ReadAttr o a | ||||||||
| writeNamedAttr :: String -> (o -> b -> IO ()) -> WriteAttr o b | ||||||||
| newAttr :: (o -> IO a) -> (o -> b -> IO ()) -> ReadWriteAttr o a b | ||||||||
| readAttr :: (o -> IO a) -> ReadAttr o a | ||||||||
| writeAttr :: (o -> b -> IO ()) -> WriteAttr o b |
| type Attr o a = ReadWriteAttr o a a | Source |
| type ReadAttr o a = ReadWriteAttr o a () | Source |
| type WriteAttr o b = ReadWriteAttr o () b | Source |
| data ReadWriteAttr o a b | Source |
| A generalised attribute with independent get and set types. | |
 Instances | |
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| data AttrOp o | Source |
| A set or update operation on an attribute. | ||||||||||||
| Constructors | ||||||||||||
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| get :: o -> ReadWriteAttr o a b -> IO a | Source |
| set :: o -> [AttrOp o] -> IO () | Source |
| newNamedAttr :: String -> (o -> IO a) -> (o -> b -> IO ()) -> ReadWriteAttr o a b | Source |
| readNamedAttr :: String -> (o -> IO a) -> ReadAttr o a | Source |
| writeNamedAttr :: String -> (o -> b -> IO ()) -> WriteAttr o b | Source |
| newAttr :: (o -> IO a) -> (o -> b -> IO ()) -> ReadWriteAttr o a b | Source |
| readAttr :: (o -> IO a) -> ReadAttr o a | Source |
| writeAttr :: (o -> b -> IO ()) -> WriteAttr o b | Source |