qlikview design best practices

Analysis of Android source code design patterns and practices (16)Chapter 2 visitor Mode Visitor mode is a behavior mode. It is the most complex of the 23 design modes. Although the frequency of use is not high, it does not mean that it can be ignored, it brings unexpected flexibility. Visitor mode, as the name implies, with this mode, you can add additional "v

Analysis of Android source code design patterns and practices (13th)Chapter 2 memorandum Model The memo mode is a behavior mode that stores the current state of an object and can be restored to this State later. It is a bit like what we usually call "regret ". 1. Definition Capture the internal state of an object without interrupting the closed state, and save the state outside the object. In this way, th

Analysis of Android source code design patterns and practices (9)Chapter 9. Responsibility Chain Model 1. Definition The responsibility chain mode is one of the behavioral design patterns. It gives multiple objects the opportunity to process requests, thus avoiding the coupling relationship between request senders and recipients. Connect these objects into a chai

the complexity of some calls, but they also enhance the flexibility of iterators, and we can manually control the process or order of iterations.4. The iterator pattern can not only iterate over algebraic groups, but also iterate over the objects of some class arrays.In JavaScript, the for-in statement can be used to iterate over the properties of an ordinary literal object.5. Reverse Iterator6. Abort iterator7. Application examples8. SummaryThe iterator pattern is a relatively simple pattern t

=function(){ This. Receiver.add ();};varDelsubmenucommand=function(receiver) { This. receiver=receiver;};D ElSubMenuCommand.prototype.execute=function{ This. Receiver.del ();}Finally, the command receiver is passed into the commands object, and the order object is bound to the buttonvar refreshmenubarcommand=New Refreshmenubarcommand (MenuBar); var addsubmenucommand=New Addsubmenucommand (submenu); var delsubmenucommand=New Delsubmenucommand (submenu); SetCommand (button1, Refreshmenu

and polymorphism.The policy model provides perfect support for the open-closed principle, encapsulating the algorithms in separate startegy, making them easy to switch, easy to understand, and easy to extend.Algorithms in the policy model can also be reused elsewhere in the system, avoiding many repetitive copy-pasting efforts.Using composition and delegation in the policy model allows the context to have the ability to execute algorithms, which is a more portable alternative to inheritance.In

iterator: Sets the callback function to the callback to return false when it jumps out of the loopExamples of applications for iterators: When file uploads are available in many ways, avoid using conditional selection statements to choose how to uploadThe solution might be: Each upload method is written as a function, the function returns the Upload object, and returns False if it is an incompatible upload method. Iterate through all the functions of the upload method as an array,

varProxysynchronousfile = (function(){7 //array of Cache IDs8 varCache = [];9 //A variable that marks whether the inertia time endsTen varTimeisnotup =NULL; One A return function(ID) { - Cache.push (ID); - if(timeisnotup) { the return; -}Else{ -Timeisnotup = SetTimeout (function(){ -Synchronousfile (Cache.join (', ') ) ); + cleartimeout (timeisnotup); -Timeisnotup =NULL; +Cache.length = 0; A}, 2000 ); at }; - } - })(); - - //Customer Act

Web-side when a large number of DOM data insertion, if a one-time insertion of thousands of data, the browser will be unable to appear in the case of the death of Kaka, the code is as follows:vararr = []; for(vari = 0; i ) {Arr.push (i);}varLoadData =function(data) { for(vari = 0, L = data.length; I ){ varElem = document.createelement (' div '); Div.innerhtml=i; Document.body.appendChild (DIV); }};loaddata (arr);//Create a Timechunk () function to insert the DOM in batchesvarTimechunk

interface object, everyone is this interface object, but a layer of layers, constantly called.The execution process is actually a depth-first search .some notable places to watchThe combined pattern is not a parent-child relationship, but rather a delegate relationship.Scenario: The combination mode is only appropriate when dealing with each leaf object in the list in a consistent manner.SummaryCombining patterns allows us to create the structure of objects in a tree-like way, and we can apply

addevent wraps the correct logical function, the code is as followsBut there is still one drawback to this function, assuming that we have not used the Addevent function from beginning to end.The third option is to use the lazy loading scheme, the first time you enter the conditional branch, the function will be overridden inside the function, the rewritten function is what we expect the Addevent function, the next time we enter the Addevent function, Addevent does not exist those branch judgme

); for(vari=0,file,files= this. files;file=files[i++]; ) {file.scan (); } }; Folder.prototype.remove=function(){ if(! this. parent) {//the root node or the free node outside the tree return; } for(varFiles = this. parent.files,l = files.length;l>=0; l--){ varFile =files[l]; if(file = = this) {files.splice (l,1); } } }; varFile =function(name) { this. Name =name; this. Parent =NULL; }; File.prototype.add=function(){ Throw