intersystems cache - Does object script supports multiple inheritance? -


i new cache , found different normal oop concept. in object script base class can inherited multiple subclasses(inheritance order can left/right). if objectscript oop, don't know how cache supports this(unlikely other programming language).

baseclass

  class inheritance.thebaseclass extends (%registeredobject,    inheritance.thechildclass, inheritance.thechildclass1) [ inheritance = left ]   {       classmethod init()      {       //do ##class(inheritance.thechildclass).ping()       //do ##class(inheritance.thechildclass1).ping()       ..ping()       ..pingggg()       }     }

child class 1

 class inheritance.thechildclass extends %registeredobject  {     classmethod ping()    {         write "i in inheritance.thechildclass",!     }   }

child class 2

class inheritance.thechildclass1 extends %registeredobject {    classmethod ping()   {     write "i in inheritance.thechildclass1",!   }    classmethod pingggg()   {     write "i in inheritance.thechildclass1111111111",!    }    }

output

i in inheritance.thechildclass

i in inheritance.thechildclass1111111111

documentation explains clearly: http://docs.intersystems.com/latest/csp/docbook/docbook.ui.page.cls?key=gobj_classes#gobj_classes_inheritance

for example, if class x inherits classes a, b, , c, definition includes:

class x extends (a, b, c)  { }

the default inheritance order class compiler left right, means differences in member definitions among superclasses resolved in favor of leftmost superclass (in case, superseding b , c, , b superseding c.)

specifically, class x, values of class parameter values, properties, , methods inherited class (the first superclass listed), class b, and, finally, class c. x inherits class members b has not defined, , class members c neither nor b has defined. if class b has class member same name member inherited a, x uses value a; similarly, if c has member same name 1 inherited either or b, order of precedence a, b, c.


Comments

Post a Comment

Popular posts from this blog

android - InAppBilling registering BroadcastReceiver in AndroidManifest -

i'm implementing inapp billing in android app. works well, however, i'm trying decouple broadcast receiver activity manifest. suggestion in android's trivialdrive sample: // important: dynamically register broadcast messages updated purchases. // register receiver here instead of <receiver> in manifest // because call getpurchases() @ startup, therefore can ignore // broadcasts sent while app isn't running. // note: registering listener in activity bad idea, done here // because sample. regardless, receiver must registered after // iabhelper setup, before first call getpurchases(). currently there's class extends broadcastreceiver : public class iabbroadcastreceiver extends broadcastreceiver { /** * intent action receiver should filter for. */ public static final string action = "com.android.vending.billing.purchases_updated"; private final iabbroadcastlistener mlistener; public iabbroadcastreceiver(iabbroadcastlistener listener) { m...
Read more

python Tkinter Capturing keyboard events save as one single string -

is possible store keyboard events 1 string? code below stores 1 char , prints it. card reader or bar code reader, contains collection of character/ string not 1 character @ time. goal save char pressed text variable. from tkinter import * root = tk() def key(event): text= event.char text+= event.char print ("pressed", text) def callback(event): frame.focus_set() print ("clicked at", event.x, event.y) frame = frame(root, width=100, height=100) frame.bind("<key>", key) frame.bind("<button-1>", callback) frame.pack() root.mainloop() currently, creating text variable , everytime key() function gets called, , text stores last character typed. you can define text module level variable , , use module level text inside key function - text = '' def key(event): global text text+= event.char print("pressed", text)
Read more

sql server - Why does Linq-to-SQL add unnecessary COUNT()? -

here tables: create table customer ( cid int primary key, name varchar(32) ) create table ord ( oid int primary key, cid int foreign key references customer, address varchar(20) ) here's linq-to-sql statement: var aaa = c in db.customer select new { c, o = c.ord.tolist() }; and here's inexplicable query generated linq-to-sql: select [t0].[cid] [cid], [t0].[name] [name], [t1].[oid] [oid], [t1].[cid] [cid2], [t1].[address] [address], (select count(*) [dbo].[ord] [t2] [t2].[cid] = [t0].[cid]) [value] [dbo].[customer] [t0] left outer join [dbo].[ord] [t1] on [t1].[cid] = [t0].[cid] order [t0].[cid], [t1].[oid] i want understand how rid of count(*) part. it's entirely uncalled for! linq needs count(*) in order determine number of entries returned o = c.ord.tolist() .
Read more