Project members: Autoobject variant

With an autoobject variant member you can override another autoobject member existing in your project. Once overridden, the variant member can retrospectively modify the properties of the original autoobject member. Autoobject variant members are represented in Composer by following bricks. Please note the additional small overlay in the icon of the brick:

The derivation of variants provides the fundamental technique to manage several product and design versions within one and the same GUI application. The selection of the appropriate variant occurs automatically depending on the condition specified in the VariantCond attribute of the variant member. Depending on this condition, Embedded Wizard distinguishes between following two types of a variant:

Type

Short description

Static

The condition for the selection of the respective variant results in a value well known at the code compilation time and immutable at the runtime. If this condition is true, the affected variant overrides the original autoobject member permanently. If the condition is false, the variant has no effect.

Dynamic

The condition for the variant selection depends on styles. Since styles can be activated and deactivated individually at the runtime, the overriding changes dynamically.

An autoobject member, which has been overridden by a variant member is considered as being multi-variant. You can derive as many variants of an original member as you want. Moreover, one autoobject variant can override another autoobject variant resulting in a hierarchy of variants. With the Browser window you can inspect this hierarchy. Please note, a member overridden by a variant is signed in the Browser with an additional small icon. You can thus recognize multi-variant members easily. Additionally, the corresponding variant condition is shown between a pair of [...] (squared brackets):

The original autoobject member is overridden by a variant, which, in turn, is overridden by another variant. Both variants specify as condition true and are thus static.

Create new autoobject variant

You create a new autoobject variant by simply deriving it from an existing autoobject or another autoobject variant. In the simplest case, if both, the original member and the variant are defined within the same unit, do following:

First ensure, that the original autoobject member is selected.

Then drag and drop the selected member while holding the keys CtrlShiftAlt pressed.

Deriving a new variant from an autoobject member existing within the same unit.

If the original member is not defined within the same unit, you can use the Browser window:

First switch to the Composer page for the respective unit member, where you want to add the new variant member.

Then ensure that the Browser window is visible.

Within the Browser locate the desired autoobject member. This can be done easily with Browser's own filter function.

Select the found autoobject member in the Browser window.

Drag and drop the selected member into the Composer area while holding the keys CtrlShiftAlt pressed.

Deriving a new variant by using the Browser window.

Alternatively, you can derive a new variant by using the clipboard functions Copy & Paste:

First ensure, that the original autoobject member is selected (e.g. in Composer, Inspector or Browser)

Press the keys CtrlC or use the menu item EDITCopy to copy the selected autoobject into the clipboard.

Eventually switch to the Composer page for the respective unit member, where you want to add the new variant.

Press the keys CtrlShiftAltV or use the menu item EDITVariant paste to add a new variant by deriving it from the autoobject stored in the clipboard.

Name the autoobject variant

First ensure, that the autoobject variant member is selected.

Press the key F2 or select the menu item EDITRename ....

Enter the new name in the Inspector window.

Variant members have a global character - they can be accessed from everywhere within your project. To address a variant member, you must always use its full name, which is composed of the unit name, the member is defined inside, and the name of the member itself, both separated by :: (double colon) signs. For example Examples::DeviceInterfaceCANBusVariant.

Specify the variant condition

The effect of an overriding depends on the condition you specify in the attribute VariantCond of the respective variant member. Per default newly derived variants are configured with the condition true. They overrides thus statically and permanently the original member. You should therefore always review this attribute after deriving a new variant.

Please note, if two variants override the same original member and both variants are configured with the same condition, Embedded Wizard will report a compilation error because of the ambiguity.

Override inherited properties

The variant exposes exact the same set of properties as the original autoobject member. When the autoobject variant is selected, you can inspect and modify these properties directly in the Inspector window. As long as not modified, a property contains the value inherited from the original member. When you modify a property, its original value is overridden.

Once overridden properties can be revert easily by pressing the keys CtrlR when the affected property is selected in Inspector. Thereupon, the value inherited from the original member is restored again.

Duplicate an existing autoobject variant

You can create any number of copies of an already existing autoobject variant member.

First ensure, that the variant member is selected.

Press the keys CtrlC and CtrlV in succession ...

... or hold the key Ctrl pressed while you drag and drop the selected variant member.

Finally rename the just duplicated autoobject variant member ...

... and review its variant condition.

You can also Drag & Drop an autoobject variant member from the Browser into the Composer window and create so a duplicate of the affected member:

First switch to the Composer page for the respective unit member, where you want to add the duplicate of the autoobject variant.

Then ensure that the Browser window is visible.

Within the Browser window locate the desired autoobject variant member. This can be done easily with Browser's own filter function.

Select this autoobject variant member in the Browser window.

Drag and drop the selected autoobject variant member into the Composer:

Duplicating an autoobject variant by simply Drag & Drop it between the Browser and Composer windows

Finally rename the just duplicated autoobject variant member ...

... and review its variant condition.

Use the autoobject variant

Embedded Wizard selects the appropriate variant automatically either at the code generation time or just at the moment when the corresponding original autoobject is evaluated within an expression. Accessing the autoobject variants individually is not possible. The selection is controlled by the attribute VariantCond.

Delete an autoobject variant

First ensure, that the variant member is selected.

Press the key DEL or select the menu item EDITDelete.

Attributes of an autoobject variant

The following table shows the complete list of attributes provided by the autoobject variant member. Please note, besides the attributes, an autoobject also exposes all properties defined in its class:

Attribute name

Short description

Brick

Determines the position and the size of an variant member brick within the Composer window.

Class

Determines the class of an autoobject member. Please note, this attribute can't be modified in derived variants.

Description

Contains the description for the variant member.

VariantCond

Determines the condition to activate a particular variant member.

VariantOf

Determines the original autoobject member to override by the variant member.