RosettaCodeData/Task/Classes/ALGOL-68/classes.alg

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MODE MYDATA = STRUCT(
INT name1
);
STRUCT(
INT name2,
PROC (REF MYDATA)REF MYDATA new,
PROC (REF MYDATA)VOID init,
PROC (REF MYDATA)VOID some method
) class my data;
class my data := (
# name2 := # 2, # Class attribute #
# PROC new := # (REF MYDATA new)REF MYDATA:(
(init OF class my data)(new);
new
),
# PROC init := # (REF MYDATA self)VOID:(
""" Constructor (Technically an initializer rather than a true 'constructor') """;
name1 OF self := 0 # Instance attribute #
),
# PROC some method := # (REF MYDATA self)VOID:(
""" Method """;
name1 OF self := 1;
name2 OF class my data := 3
)
);
# class name, invoked as a function is the constructor syntax #
REF MYDATA my data = (new OF class my data)(LOC MYDATA);
MODE GENDEROPT = UNION(STRING, VOID);
MODE AGEOPT = UNION(INT, VOID);
MODE MYOTHERDATA = STRUCT(
STRING name,
GENDEROPT gender,
AGEOPT age
);
STRUCT (
INT count,
PROC (REF MYOTHERDATA, STRING, GENDEROPT, AGEOPT)REF MYOTHERDATA new,
PROC (REF MYOTHERDATA, STRING, GENDEROPT, AGEOPT)VOID init,
PROC (REF MYOTHERDATA)VOID del
) class my other data;
class my other data := (
# count := # 0, # Population of "(init OF class my other data)" objects #
# PROC new := # (REF MYOTHERDATA new, STRING name, GENDEROPT gender, AGEOPT age)REF MYOTHERDATA:(
(init OF class my other data)(new, name, gender, age);
new
),
# PROC init := # (REF MYOTHERDATA self, STRING name, GENDEROPT gender, AGEOPT age)VOID:(
""" One initializer required, others are optional (with different defaults) """;
count OF class my other data +:= 1;
name OF self := name;
gender OF self := gender;
CASE gender OF self IN
(VOID):gender OF self := "Male"
ESAC;
age OF self := age
),
# PROC del := # (REF MYOTHERDATA self)VOID:(
count OF class my other data -:= 1
)
);
PROC attribute error := STRING: error char; # mend the error with the "error char" #
# Allocate the instance from HEAP #
REF MYOTHERDATA person1 = (new OF class my other data)(HEAP MYOTHERDATA, "John", EMPTY, EMPTY);
print (((name OF person1), ": ",
(gender OF person1|(STRING gender):gender|attribute error), " ")); # "John Male" #
print (((age OF person1|(INT age):age|attribute error), new line)); # Raises AttributeError exception! #
# Allocate the instance from LOC (stack) #
REF MYOTHERDATA person2 = (new OF class my other data)(LOC MYOTHERDATA, "Jane", "Female", 23);
print (((name OF person2), ": ",
(gender OF person2|(STRING gender):gender|attribute error), " "));
print (((age OF person2|(INT age):age|attribute error), new line)) # "Jane Female 23" #