derived

问题 My problem in brief: class A { /* Other stuff in my class*/ protected static staticMember; } class B : A { /* Other stuff in my class*/ // Will have A.staticMember but I want B.staticMember (same type) } class C : A { /* Other stuff in my class*/ // Will have A.staticMember but I want C.staticMember (same type) } So I want all my derived class to have a shared data that is shared for that paricular class but have a common signature defined in the base class. I'm creating a simple RTS game for

问题 I have this trigger : CREATE trigger [dbo].[DeriveTheAge] on [dbo].[Student] after insert,update as begin declare @sid as int; declare @sdate as date; select @sid= [Student ID] from inserted; select @sdate=[Date of Birth] from inserted; commit TRANSACTION if(@sdate is not null) begin update Student set Age=DATEDIFF(YEAR,@sdate,GETDATE()) where [Student ID]=@sid; end print 'Successfully Done' end as it suggests, the trigger automatically calculates the Derived attribute "Age" from the date of

问题 There is a dynamically allocated struct: TYPE Struct INTEGER :: N REAL*8 :: A REAL*8,ALLOCATABLE :: B(:) END TYPE Struct and it has a dynamically allocated memeber : B(:) When I try to use MPI_TYPE_CREATE_STRUCT to create a derived datatype for such Struct, it happens that differen CPUs create inconsistent derived datatypes. This is because Struct%B(:) might be located in different memory locations relative to the first memeber Struct%N, on different CPUs. Then MPI_SEND( Struct,...) won't

问题 There is a dynamically allocated struct: TYPE Struct INTEGER :: N REAL*8 :: A REAL*8,ALLOCATABLE :: B(:) END TYPE Struct and it has a dynamically allocated memeber : B(:) When I try to use MPI_TYPE_CREATE_STRUCT to create a derived datatype for such Struct, it happens that differen CPUs create inconsistent derived datatypes. This is because Struct%B(:) might be located in different memory locations relative to the first memeber Struct%N, on different CPUs. Then MPI_SEND( Struct,...) won't

问题 I am trying to get the derived type of an object via a base class virtual function. I have written this, which does not compile: struct base { virtual base& get_this() { return *this; } }; struct derived : base { virtual derived& get_this() override { return *this; } void fn(); }; int main () { base* pd = new derived(); derived& x = pd->get_this(); /*ERROR*/ x.fn(); return 0; } ... giving me an error that: I cannot initialize a derived& from a base . Since get_this is virtual, why does pd-

问题 There seems to be no good online documentation on this: If I make a derived class, will it automatically have all the attributes of the base class? But what's the BaseClass.__init() for, do you also need to do it to other base class methods? Does BaseClass.__init__() need arguments? If you have arguments for your base class __init__() , are they also used by the derived class, do you need to explicitly set the arguments to the derived classe's __init__() , or set them to BaseClass.__init__()

问题 Since mysql does not enforce the Single-Value Rule (See: https://stackoverflow.com/a/1646121/1688441) does a derived table with an order by guarantee which row values will be displayed? This is for columns not in an aggregate function and not in the group by . I was looking at the question (MySQL GROUP BY behavior) after having commented on and answered the question (https://stackoverflow.com/a/24653572/1688441) . I don't agree with the accepted answer, but realized that a possible improved

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . This question has always been around my head. Can someone create a new product based on an existing open source project? Say you want to create an "Apaxe webserver" that is basically Apache with your some extra plugins ( say support for ASP or something similar ) Is this possible? Would you be able to create a

问题 I am trying to create a scene or state manager which stores a Dictionary for each state as a way to load or change the state of the program (for example, a Main Menu state and a Game state). I have a bunch of derived classes of base class State that have variables that are not included in the base State class. Am I able to safely store them in this Dictionary? Will I have any data loss? If this doesn't work, what are alternative methods to achieve my goal? 回答1: This seems like something you

问题 I have an issue in creating a derived column that I can't seem to figure out. It's simple SQL, but in SSIS I can't seem to do it. Basically it is checking for a value greater than zero, and assigning a string result. The resul needs to be wrapped in a string as well. Example: "Indicator=\"" + [IND] > 0 ? "CP" : "" + "\"" Should yield: Indicator = "CP" if IND is 20.00 or Indicator = "" if IND is 0 I cannot seem to mix the If/Then with the strings. Anyone have an idea? 回答1: You were on the