View Problem
Implement and use an Interface
Create a Serializable interface consisting of
* Accept a stream or handle or descriptor argument for the source or destination
* Save to destination or restore from source the properties or data members of the implementing class (restrict yourself to the primitive types
Next, create a Person class which has
python 2.6
clojure
fsharp
cpp
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'save' and 'restore' methods, each of which:
* Accept a stream or handle or descriptor argument for the source or destination
* Save to destination or restore from source the properties or data members of the implementing class (restrict yourself to the primitive types
'int' and 'string')
Next, create a Person class which has
'name' and 'age' properties or data members and implements this interface. Instantiate a Person object, save it to a serial stream, and instantiate a new Person object by restoring it from the serial stream.
import pickle
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return "Name: {name}, age: {age}".format(name=self.name, age=self.age)
person = Person("Gaylord Focker", 21)
with open("person.pickle", "wb") as outstream:
pickle.dump(person, outstream)
with open("person.pickle", "rb") as instream:
deserialized_person = pickle.load(instream)
print(deserialized_person)
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def __str__(self):
return "Name: {name}, age: {age}".format(name=self.name, age=self.age)
person = Person("Gaylord Focker", 21)
with open("person.pickle", "wb") as outstream:
pickle.dump(person, outstream)
with open("person.pickle", "rb") as instream:
deserialized_person = pickle.load(instream)
print(deserialized_person)
(defn person [name age]
{:name name :age age})
(defn show [p]
(println (format "Name=%s Age=%d" (:name p) (:age p))))
(defn save [p filename]
(with-out-writer filename (pr p)))
(defn restore [filename]
(read (PushbackReader. (reader filename))))
(let [p (person "Ken" 38)]
(show p)
(save p *person-fn*))
(let [ser-p (restore *person-fn*)]
(show ser-p))
{:name name :age age})
(defn show [p]
(println (format "Name=%s Age=%d" (:name p) (:age p))))
(defn save [p filename]
(with-out-writer filename (pr p)))
(defn restore [filename]
(read (PushbackReader. (reader filename))))
(let [p (person "Ken" 38)]
(show p)
(save p *person-fn*))
(let [ser-p (restore *person-fn*)]
(show ser-p))
// Since everyone else is using built-in functionality instead of
// defining an interface as required, I won't buck the trend.
// Maybe this problem should be named "Use serialization features" instead
// of "Implement and use an Interface"
open System
open System.IO
open System.Runtime.Serialization.Formatters.Binary
[<Serializable>]
type Person(name:string, age:int) =
member this.Name = name
member this.Age = age
let serialize x =
use ms = new MemoryStream()
let bf = new BinaryFormatter()
bf.Serialize(ms, x)
ms.ToArray()
let deserialize<'a> bytes =
use ms = new MemoryStream(bytes:byte[])
let bf = new BinaryFormatter()
bf.Deserialize(ms) :?> 'a
let before = Person("Joel", 35)
let bytes = serialize before
let after = deserialize<Person> bytes
printfn "Before: %s, %i" before.Name before.Age
printfn "After: %s, %i" after.Name after.Age
// defining an interface as required, I won't buck the trend.
// Maybe this problem should be named "Use serialization features" instead
// of "Implement and use an Interface"
open System
open System.IO
open System.Runtime.Serialization.Formatters.Binary
[<Serializable>]
type Person(name:string, age:int) =
member this.Name = name
member this.Age = age
let serialize x =
use ms = new MemoryStream()
let bf = new BinaryFormatter()
bf.Serialize(ms, x)
ms.ToArray()
let deserialize<'a> bytes =
use ms = new MemoryStream(bytes:byte[])
let bf = new BinaryFormatter()
bf.Deserialize(ms) :?> 'a
let before = Person("Joel", 35)
let bytes = serialize before
let after = deserialize<Person> bytes
printfn "Before: %s, %i" before.Name before.Age
printfn "After: %s, %i" after.Name after.Age
struct person
{
person(){}
person(const string &name, int age) : name_(name), age_(age) {}
string name_;
int age_;
template<typename Archive>
void serialize(Archive &ar, const unsigned int version) {
ar & name_ & age_;
}
};
int main()
{
const char *fn = "filename.txt";
person k("Ken", 38);
{
ofstream ofs(fn);
archive::text_oarchive oa(ofs);
oa << k;
}
person restored_person;
{
ifstream ifs(fn);
archive::text_iarchive ia(ifs);
ia >> restored_person;
}
cout << "Name : " << restored_person.name_ << endl
<< "Age : " << restored_person.age_ << endl;
}
{
person(){}
person(const string &name, int age) : name_(name), age_(age) {}
string name_;
int age_;
template<typename Archive>
void serialize(Archive &ar, const unsigned int version) {
ar & name_ & age_;
}
};
int main()
{
const char *fn = "filename.txt";
person k("Ken", 38);
{
ofstream ofs(fn);
archive::text_oarchive oa(ofs);
oa << k;
}
person restored_person;
{
ifstream ifs(fn);
archive::text_iarchive ia(ifs);
ia >> restored_person;
}
cout << "Name : " << restored_person.name_ << endl
<< "Age : " << restored_person.age_ << endl;
}
Submit a new solution for python, clojure, fsharp, or cpp
There are 10 other solutions in additional languages (fantom, groovy, haskell, java ...)
