Really nice to have SeExpr in Clarisse. Powerful stuff. 🙂

How to use expressions:

• Click the Sum (Σ, Sigma) symbol right at the attribute and type the expression.
• You can “bake” the expression with Ctrl+LMB (on the Sum symbol).
• You can click the Sum symbol to see the result not the expression itself. (You can do this globally at the top of the Attribute Editor’s Sum sign.)

Examples:

Easy way to get random rotation with every duplicate (duplicate selected object):
Activate the expression panel by clicking the Σ symbol, then type: rand(0,360)

Create a link to a Render Image/layer’s active camera attribute (relative path – the two render images are at the same hierarchy level: inside the same context):
get_string("main_R_Image.mainLayer.active_camera")
main_R_Image: nem of the Render Image
mainLayer: name of the layer
active_camera: name of the attribute

Create a link to a Render Image/layer’s active camera attribute (full path):
get_string("project://shotMain/renderImage/main_R_Image.mainLayer.active_camera")
project://shotMain/renderImage/: is the full path to the Render Image

Link to a float value inside the same object (node):
get_double("size[0]")
In this case size[0] means size in X direction

To grab the name of the current object use:
get_name()

To grab the name of the context use:
get_name(get_context())

Easy to concatenate as well (like in python):
“some_text/” + get_name(get_context()) + “/” + get_name()

Dynamic object search:
Find the first camera inside an alembic (or usd) file:
find_object("target_path/*", "Camera")
The target_path can be relative or absolute as well, the same syntax as in Groups.
Related doc:
https://clarissewiki.com/4.0/constant-and-functions-referen.html

Open the Log in Clarisse to get precise attributes and paths (change a value and check the results).

Use the … to pop up an Expression Editor window.

You can use Global Variables as well.
https://clarissewiki.com/4.0/using-global-variables.html

For more details check the Clarisse documentation:
https://clarissewiki.com/4.0/attribute-types-and-expression.html

A great introduction for Clarisse Expressions:
https://youtu.be/4y8fbBi5quU