# control.gui_dict:var


Variable storage for implementing with qt GUI.


Usage

``` python
control.gui_dict:var(
    *args,
    **kwargs,
)
```


One [var](control.gui_dict.var.md#matr1x.control.gui_dict.var) is one row of a control panel: it stores the current value, the Qt widgets that display and edit it (see [widgets](control.gui_dict.var.md#matr1x.control.gui_dict.var.widgets)), and the metadata of the row.

Emits valueChanged signal if the value has changed so it can be connected to a display.


## Parameters


`dtype: type or None`  
Type of the value (`float`, `int`, `str`, …). Also the first positional argument.

`columns: list[guiObject] or guiObject`  
Widget type(s) of the row, typically two entries: readout and setpoint. A plain `str` is shown as a static label.

`unit: str`  
Unit string, shown in the label and written to the log file.

`log: bool`  
Log the value by default, i.e. after start-up. Requires `dtype` to be set.

`init: object or list`  
Initial content of the column(s): values, spin box ranges, combo box entries or button texts. A single object is applied to both columns.

`hide: bool`  
Hide the row unless the "extended" view is enabled.

`modify: MethodBundle or list`  
[MethodBundle](control.gui_dict.MethodBundle.md#matr1x.control.gui_dict.MethodBundle)(s) applied to the column widget(s) for custom setup and value change handling.


## Notes

Setting [value](control.gui_dict.var.md#matr1x.control.gui_dict.var.value) updates the readout widget and triggers any change handlers. Use [getGUIvalue()](control.gui_dict.var.md#matr1x.control.gui_dict.var.getGUIvalue) to read the value as entered in the setpoint widget.


## Attributes

| Name | Description |
|----|----|
| [tooltip](#tooltip) | Get the tooltip of the variable. |
| [unit](#unit) | Get the unit of the variable. |
| [value](#value) | Get the current value of the variable. |
| [widgets](#widgets) | Get the Qt widgets of the variable row. |

------------------------------------------------------------------------


### tooltip


Get the tooltip of the variable.


`tooltip: str`


------------------------------------------------------------------------


### unit


Get the unit of the variable.


`unit: str`


------------------------------------------------------------------------


### value


Get the current value of the variable.


`value: Any`


------------------------------------------------------------------------


### widgets


Get the Qt widgets of the variable row.


`widgets: list[Any]`


## Methods

| Name | Description |
|----|----|
| [__init__()](#__init__) | Initialize the variable storage. |
| [copy_value()](#copy_value) | Copy the read values into the set field. |
| [getGUIvalue()](#getGUIvalue) | Return the value of the GUI element in the respective column. |
| [setValue()](#setValue) | Set the value of the variable. |

------------------------------------------------------------------------


### \_\_init\_\_()


Initialize the variable storage.


Usage

``` python
__init__(
    self,
    dtype: type | None,
    columns: list[guiObject | str | None] | str | guiObject | None = None,
    unit: str = '',
    log: bool | None = False,
    init: object | None = None,
    hide: bool = False,
    modify: MethodBundle | list[MethodBundle | None] | None = None,
) -> None
__init__(
    self,
    __dtype: type | None,
) -> None
```


------------------------------------------------------------------------


### copy_value()


Copy the read values into the set field.


Usage

``` python
copy_value()
```


Thread-safe: emits copyValueRequested, which Qt dispatches to the GUI thread via a queued connection when called from a worker thread, and as a direct call when already on the GUI thread.


------------------------------------------------------------------------


### getGUIvalue()


Return the value of the GUI element in the respective column.


Usage

``` python
getGUIvalue(column=2)
```


On the widget-owning thread the widget is read directly. Otherwise a cached GUI value is returned when available.


#### Parameters


`column: int = ``2`  
Column index in the widget list to read the value from.


#### Returns


`Any`  
The value from the GUI element, cast to variableType.


#### Raises


`RuntimeError`  
If the method is called off the widget-owning thread and no thread-safe value source is available.


------------------------------------------------------------------------


### setValue()


Set the value of the variable.


Usage

``` python
setValue(newValue)
```


#### Parameters


`newValue: Any`  
The new value to set.