oop

问题 I have an abstract class. I want to extend the abstract class by another abstract class and then implement the extended abstract class. Is it possible .If yes, whether it's a good approach in point of view regarding OOPS? 回答1: I'm not sure about Java in particular, but it should be valid. In terms of OOP, if it makes sense, then run with it. To use some old examples, you might have a Vehicle abstract class and then LandVehicle and FlyingVehicle abstract classes. As long as your example makes

问题 I have an abstract class. I want to extend the abstract class by another abstract class and then implement the extended abstract class. Is it possible .If yes, whether it's a good approach in point of view regarding OOPS? 回答1: I'm not sure about Java in particular, but it should be valid. In terms of OOP, if it makes sense, then run with it. To use some old examples, you might have a Vehicle abstract class and then LandVehicle and FlyingVehicle abstract classes. As long as your example makes

问题 How does a handle differ from a pointer to an object and also why can't we have a reference to a reference? 回答1: A handle is usually an opaque reference to an object. The type of the handle is unrelated to the element referenced. Consider for example a file descriptor returned by open() system call. The type is int but it represents an entry in the open files table. The actual data stored in the table is unrelated to the int that was returned by open() freeing the implementation from having

问题 I need help to figure out why this is error <?php class data { private $db; public $nama, $password, $alamat, $jk, $kodepos, $alasan, $email; function _construct($db) { $this->db = $db; } public function input_data() { $query = "INSERT INTO data (nama, password, alamat, jeniskelamin, kodepos, alasan, email)VALUES('$this->nama', '$this->password', '$this->alamat', '$this->jk', '$this->kodepos', '$this->alasan', '$this->email')"; $insert = mysqli_query($this->db, $query); return $insert; }

问题 I need help to figure out why this is error <?php class data { private $db; public $nama, $password, $alamat, $jk, $kodepos, $alasan, $email; function _construct($db) { $this->db = $db; } public function input_data() { $query = "INSERT INTO data (nama, password, alamat, jeniskelamin, kodepos, alasan, email)VALUES('$this->nama', '$this->password', '$this->alamat', '$this->jk', '$this->kodepos', '$this->alasan', '$this->email')"; $insert = mysqli_query($this->db, $query); return $insert; }

问题 I am using some code that uses the singleton-version of matplotlib in Python, i.e. it has calls like plt.figure() ... plt.xlabel("abc") I am trying to convert it to the functional/memory-less version: fig,ax = plt.subplots() ... ax.set_xlabel("abc") A couple questions: Is there an option to set the xlabel of an axes directly? Something like ax.xlabel = "xlabel string" ? From the documentation, it seems like this is not possible. (not even a private attribute we can set) Or is it always

问题 I am using some code that uses the singleton-version of matplotlib in Python, i.e. it has calls like plt.figure() ... plt.xlabel("abc") I am trying to convert it to the functional/memory-less version: fig,ax = plt.subplots() ... ax.set_xlabel("abc") A couple questions: Is there an option to set the xlabel of an axes directly? Something like ax.xlabel = "xlabel string" ? From the documentation, it seems like this is not possible. (not even a private attribute we can set) Or is it always

问题 I am trying to understand how class inheritance works in Python 3, in particular how private fields interact with local and inherited methods. Here are some examples to illustrate the issue. First, if a variable var in the Superclass is public, then any method in the Subclass will also be able to alter it: class Superclass: var = 1 def getVar(self): print(self.var) class Subclass(Superclass): def __init__(self): self.var = 123 my_object = Subclass() my_object.getVar() # outputs 123 The same

问题 I am trying to understand how class inheritance works in Python 3, in particular how private fields interact with local and inherited methods. Here are some examples to illustrate the issue. First, if a variable var in the Superclass is public, then any method in the Subclass will also be able to alter it: class Superclass: var = 1 def getVar(self): print(self.var) class Subclass(Superclass): def __init__(self): self.var = 123 my_object = Subclass() my_object.getVar() # outputs 123 The same

问题 I was wondering if anyone had any good ways of quickly explaining how to efficiently and pythonically create user defined objects with optional arguments. For instance, I want to create this object: class Object: def __init__(self, some_other_object, i, *j, *k): self.some_other_object = some_other_object self.i = i # If j is specified, assume it is = i if(j==None): self.j = i else: self.j = j # If k is given, assume 0 if(k==None): self.k = 0 else: self.k = k Is there a better way to do this?