In reply to arquer:
SV LRM: “an interface can also contain processes (i.e., initial or always procedures) and continuous assignments, which are useful for system-level modeling and testbench applications.”
Please be clear about the signal in your interface is declared as “variable” or “net”.
A net can be written by one or more continuous assignments, by primitive outputs, or through module ports. The resultant value of multiple drivers is determined by the resolution function of the net type. A net cannot be procedurally assigned.
Variables can be written by one or more procedural statements, including procedural continuous assignments. The last write determines the value. Alternatively, variables can be written by one continuous assignment or one port.
You can have a continuous assignment to a variable. But when you do so,you can only have one continuous assignment and no other procedural assignments at the same time.