UVL Download is broken in some cases

[derf]

Hi,

When going along the Tutorial given at MODEVAR/Re:Volution just now, I encountered an error when using "Export To" → "Download UVL" in ide.flamapy.org.

Feature model:

features
	Pizza {Allergens {Cereals, Milk, Sulphites}, Units {Price 'Eur'},
			constraint Price == sum(Pizza, Price)}
		mandatory
			Integer OrderNum
			String CustomerName
			Base {abstract}
				mandatory
					Mozzarella
					Oregano
				optional
					Tomato
		optional
			Ingredients cardinality [1..6] {abstract, Price 1.00}
				alternative
					"York Ham"
					Mushroom
					Peppers
			Vegan
			Calzone
			Size {abstract}
				alternative
					Normal {Price 6.00}
					Big {Price 8.50}
constraints
	Calzone => !Size & !Calzone => Size
	Big => Ingredients.Price == Ingredients.Price + 0.50
	OrderNum > 0
	len(CustomerName) > 0

Error:

Traceback (most recent call last): File "/lib/python312.zip/_pyodide/_base.py", line 596, in eval_code_async await CodeRunner( File "/lib/python312.zip/_pyodide/_base.py", line 410, in run_async coroutine = eval(self.code, globals, locals) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "<exec>", line 2, in <module> File "<exec>", line 125, in execute_export_transformation File "/lib/python3.12/site-packages/flamapy/core/discover.py", line 163, in use_transformation_m2t return plugin.use_transformation_m2t(src, dst) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/core/plugins.py", line 105, in use_transformation_m2t return result.transform() ^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py", line 56, in transform self.read_features(root, "features", 0) + "\n" + self.read_constraints() ^^^^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py", line 137, in read_constraints constraint_text = self.serialize_constraint(constraint) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/metamodels/fm_metamodel/transformations/uvl_writer.py", line 149, in serialize_constraint str_constraint = ctc.ast.pretty_str() ^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/core/models/ast.py", line 194, in pretty_str return self.root.pretty_str() ^^^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/core/models/ast.py", line 115, in pretty_str left = Node._get_pretty_str_node(self.left) if self.left is not None else '' ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/core/models/ast.py", line 106, in _get_pretty_str_node res = f'{node.pretty_str()}' ^^^^^^^^^^^^^^^^^ File "/lib/python3.12/site-packages/flamapy/core/models/ast.py", line 127, in pretty_str return res ^^^ UnboundLocalError: cannot access local variable 'res' where it is not associated with a value 

Thanks for giving the tutorial by the way, I didn't know that UVL had come this far over the past years :)

[sebasruii]

Hi @derf ,

Thank you for participating in the tutorial and also submitting this issue! I have identified the cause of the error and will be working on a fix.

Error cause:
len(CustomerName) > 0
Although the UVL model is syntactically valid, line 29 cannot be processed in flamapy, as currently string restrictions are not supported. The download button triggers a prior model processing using flamapy in order to convert the model to the desired output format, which raises the error. Nevertheless, in the case of a syntactically valid UVL model, flamapy processing should not be triggered, which would allow to download the model.

Thanks again! :)