class-members

问题 class MetaData(): maxSize = 2**10 # class definition code if not os.path.exists('sample.data'): SSD = open('sample.data', 'wb+') data = { 0: [], 1: {'.': None,} } data[1]['~'] = data[1] MetaData.save() # i want to call the save function here # class function @classmethod def save(cls): cls.SSD.seek(0) cls.SSD.write(b' ' * cls.maxSize) cls.SSD.seek(0) cls.SSD.write(pickle.dumps(cls.data)) I want to use the save() function inside the class block. I've tried MetaDate.save() and simply save()

问题 Is there a way to convert string or characters to class member/member functions to access them dynamically? for ex. this particular code, #include <iostream> #include <map> using namespace std; class agnt { public: int x, y; agnt(int a=0, int b=0) : x(a), y(b) {} }; int main() { map<int,agnt> agntID; agnt temp; temp.x=1; temp.y=5; agntID[1]=temp; for(char tmp='x'; tmp<'z'; tmp++) { cout<<agntID[1].tmp<<'\n'; //Here I get the following error: tmp is } //not a member of class agnt } Is there a

问题 I have class with final String as unique ID. Of course I want to override equals so comparison is based on ID only. Is it correct practice then to just return hash code of ID, like below? class ItemSpec{ final String name; ... @Override public boolean equals(Object o){ if(o != null && o instanceof ItemSpec){ return name.equalsIgnoreCase(((ItemSpec)o).name); } else{ return false; } } @Override public int hashCode(){ if(name == null){ return 0; } else{ return name.hashCode(); } } } 回答1: Not if

问题 I have class with final String as unique ID. Of course I want to override equals so comparison is based on ID only. Is it correct practice then to just return hash code of ID, like below? class ItemSpec{ final String name; ... @Override public boolean equals(Object o){ if(o != null && o instanceof ItemSpec){ return name.equalsIgnoreCase(((ItemSpec)o).name); } else{ return false; } } @Override public int hashCode(){ if(name == null){ return 0; } else{ return name.hashCode(); } } } 回答1: Not if

问题 I was wondering if it is good practice to use the member operator . like this: someVector = (segment.getFirst() - segment.getSecond()).normalize().normalCCW(); Just made that to show the two different things I was wondering, namely if using (expressions).member/function() and foo.getBar().getmoreBar() were in keeping with the spirit of readability and maintainability. In all the c++ code and books I learned from, I've never seen it used in this way, yet its intoxicatingly easy to use it as

问题 I'm designing a dynamic buffer for outgoing messages. The data structure takes the form of a queue of nodes that have a Byte Array buffer as a member. Unfortunately in VBA, Arrays cannot be public members of a class. For example, this is a no-no and will not compile: 'clsTest Public Buffer() As Byte You will get the following error: "Constants, fixed-length strings, arrays, user-defined types and Declare statements not allowed as Public members of object modules" Well, that's fine, I'll just

问题 i defined a class in header file and implemented its function in same header file. but while defining these functions i have to put inline keyword with function definition. Otherwise compiler gave compile time error. I know inline is only a hint to compiler. So why it is necessary to put inline keyword with function definition. I am using visual studio compiler with qt for compiling the code here is the code tempinline.h #ifndef TEMPINLINE_H #define TEMPINLINE_H #include "iostream" class

问题 I have a record class like this : public class RecordInfo { public String CDate; public String Patient_ID; public Color Zone; public String Fname; public String Lname; public Int64 ImgSize; public String ImagePrefix; public String ImagePath; public String Sex; public String TZ; } and I made a list of RecordInfo like this : List<RecordInfo> PatientRecords = new List<RecordInfo>(); and I added records to it, but I would like to sort that list based on Patient_ID, sex, Fname, etc..... Any idea

问题 I have a function that potentially moves a generic argument but through their members. What of these options is more correct: This seems the more natural but it is strange because the argument is potentially moved twice [a], which is odd because the object can become invalid. template<class T> void fun(T&& t){ myhead_ = std::forward<T>(t).head_; myrest_ = std::forward<T>(t).rest_; } This can't be incorrect but it may not be moving anything. template<class T> void fun(T&& t){ myhead_ = std:

问题 I have a function that potentially moves a generic argument but through their members. What of these options is more correct: This seems the more natural but it is strange because the argument is potentially moved twice [a], which is odd because the object can become invalid. template<class T> void fun(T&& t){ myhead_ = std::forward<T>(t).head_; myrest_ = std::forward<T>(t).rest_; } This can't be incorrect but it may not be moving anything. template<class T> void fun(T&& t){ myhead_ = std: