Hello, I have a question about Scripted Value Constraints.
I want to create new type check for UUID value, like this:
::nx::Slot method name=uuid {name value} { if {[regexp {([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12})} $value] != 1} { error "Value '$value' of parameter $name is not UUID" } }
So the tutorial states: If the same checks are used in many places in the program, defining names for the value checker will be the better choice since it improves maintainability.
This part is kinda blurry for me, what does it means define a name? For example, how can I use for example:
nx::Class create myClass -superclass mySupaClass { :property {user:uuid,required} :property {client:object,required} :property {total 0}
bla bla bla
Thank you
Hi Maksym!
To define your custom and named "value-type checker" (uuid), either for object parameters, method parameters, or both, you have to define a corresponding method on two built-in objects:
... on ::nx::ObjectParameterSlot for the scope of object parameters; ... on ::nx::methodParameterSlot for the scope of method parameters;
Watch:
::nx::ObjectParameterSlot method type=uuid {name value} { set pattern {^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$} if {![regexp $pattern $value]} { error "Value '$value' of parameter $name is not UUID" } return $value }
nx::Class create myClass { :property -accessor public {user:uuid,required} }
set obj [myClass new -user 5a40e63a-9317-11ed-a1eb-0242ac120002]; # ok puts [$obj user get]
myClass new -user nope-9317-11ed-a1eb-0242ac120002; # not ok
Some more remarks:
- the method names must carry the prefix "type="; - the checker methods must return the validated value (or, a derived one); - To create a method-parameter checker, you have to define an object method "type=uuid" on ::nx::methodParameterSlot, like:
::nx::methodParameterSlot object method type=uuid {name value} { set pattern {^[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}$} if {![regexp $pattern $value]} { error "Value '$value' of parameter $name is not UUID" } return $value }
(Note the difference: "object" modifier!)
... to avoid a duplicated and use a shared definition, you may create an alias:
set m [::nx::ObjectParameterSlot method type=uuid {name value} { # stripped for clarity }]
::nx::methodParameterSlot object alias type=uuid $m
Then, you can use:
myClass public method foo {user:uuid} { puts "Accepted: $user" }
$obj foo 5a40e63a-9317-11ed-a1eb-0242ac120002; # ok $obj foo nope-9317-11ed-a1eb-0242ac120002; # not ok
This part is kinda blurry for me, what does it means define a name?
"Name" refers to a custom, self-chosen name "uuid", that can be then used to specify value constraints on object and/ or method parameters.
If you have ideas, suggestions for improvement regarding documentation, we will be happy to consider them.
HTH, Stefan
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Maksym Zinchenko -
Stefan Sobernig