object-Z specification of credit card using eclipse - z-notation

Question

i am currently trying to run an example of object-Z specification for the CreditCard class, but i encountered a problem when declaring the visibility list and INIT schema.Is there any way to fix this ? Thank you for reading
visibility list says the items are not features of the class
undeclared name : balance

Answer 1

I'm not sure CZT copes well with Object Z.
For an example of a big Z specification, I suggest this recently uploaded project:
https://github.com/vinahradau/finma
For the credit card example, I created this schema (CZT and then converted into latex), which executes well in jaza.
CZT:
┌ LIMIT
limit: ℤ
|
limit ∈ {1000, 2000, 5000}
└
┌ BALANCE
ΞLIMIT
balance: ℤ
|
balance + limit ≥ 0
└
┌ Init
BALANCE ′
|
balance′ = 0
└
┌ SetLimit
ΔLIMIT
limit?: ℕ
|
limit′ = limit?
└
┌ Withdraw
ΔBALANCE
amount?: ℕ
|
amount? ≤ balance + limit
balance′ = balance − amount?
└
┌ Deposit
ΔBALANCE
amount?: ℕ
|
balance′ = balance + amount?
└
┌ WithdrawAvail
ΔBALANCE
amount!: ℕ
|
amount! = balance + limit
balance′ = -limit
└
Latex:
\begin{schema}{LIMIT}
limit : \num
\where
limit \in \{ 1000 , 2000 , 5000 \}
\end{schema}
\begin{schema}{BALANCE}
\Xi LIMIT \\
balance : \num
\where
balance + limit \geq 0
\end{schema}
\begin{schema}{Init}
BALANCE~'
\where
balance' = 0
\end{schema}
\begin{schema}{SetLimit}
\Delta LIMIT \\
limit? : \nat
\where
limit' = limit?
\end{schema}
\begin{schema}{Withdraw}
\Delta BALANCE \\
amount? : \nat
\where
amount? \leq balance + limit \\
balance' = balance - amount?
\end{schema}
\begin{schema}{Deposit}
\Delta BALANCE \\
amount? : \nat
\where
balance' = balance + amount?
\end{schema}
\begin{schema}{WithdrawAvail}
\Delta BALANCE \\
amount! : \nat
\where
amount! = balance + limit \\
balance' =~\negate limit
\end{schema}
Jaza:
JAZA> load C:\jaza\creditcard.
Loading 'C:\jaza\creditcard.' ...
Added 7 definitions.
JAZA> do Init
\lblot balance'==0, limit'==1000, limit''==1000 \rblot
JAZA> ; SetLimit
Input limit? = 1000
\lblot balance'==0, limit'==1000 \rblot
JAZA> ; Deposit
Input amount? = 10
\lblot balance'==10, limit'==1000, limit''==1000 \rblot
JAZA>
JAZA>
JAZA>
JAZA> ; Withdraw
Input amount? = 5
\lblot balance'==5, limit'==1000, limit''==1000 \rblot
JAZA> ; WithdrawAvail
\lblot amount!==1005, balance'==-1000, limit'==1000, limit''==1000 \rblot
JAZA>