Dimensional Data

In this tutorial, you will learn how to use return type deduction in C++ Builder. For the C++14 scheme of auto with functions, the compiler can deduce return types for any function, no matter how complex it is. The only requirement is that each return statement needs have the same type. The practices are identical as for auto variables. To deduce the type, the compiler requires to detect the function definition right ahead. That means this technique is limited to function templates, inline functions, and helper functions which are applied only inside a particular translation unit. Here is a code example on return type deduction #ifdef _WIN32 #include #else typedef char _TCHAR; #define _tmain main #endif #include #include class employee { // Lots of code here }; struct person_id { std::string first_name; std::string last_name; }; class employees { public: auto find_employee(const std::string& name) { return 1; } }; int return_an_int() { return 1; } auto return_something() { return 1; } // The following will give a compiler error, because int and // float are different types //auto returnConfusion() { // if (std::rand() %2 == 0) { // return -1; // } else { // return 3.14159; // } //} int main() { auto i{ return_an_int() }; auto j{ return_something() }; // Example of a method with multiple return points, each with different types – an error // auto k {returnConfusion()}; auto employee_list{ std::make_unique() }; auto person = employee_list->find_employee(“Jane Smith”); system(“pause”); return 0; } 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 #ifdef _WIN32 #include #else typedef char _TCHAR; #define _tmain main #endif   #include #include   class employee {     // Lots of code here };   struct person_id {     std::string first_name;     std::string last_name; };   class employees { public:     auto find_employee(const std::string& name) { return 1; } };   int return_an_int() {     return 1; }   auto return_something() {     return 1; }   // The following will give a compiler error, because int and //     float are different types //auto returnConfusion() { //    if (std::rand() %2 == 0) { //        return -1; //    } else { //        return 3.14159; //    } //} int main() {     auto i{ return_an_int() };       auto j{ return_something() };       // Example of a method with multiple return points, each with different types – an error     // auto k {returnConfusion()};       auto employee_list{ std::make_uniqueemployees>() };       auto person = employee_list->find_employee(“Jane Smith”);       system(“pause”);     return 0; } So, return type deduction bypasses undesirable conversions and the removes type changes you must to apply. If there is a possibility to use return type deduction, just apply this technique. Because this can assist to secure the types you utilize more consistently. Check out more modern C++ features over here on GitHub

Launch the License Manager from the bin folder (by default “C:Program Files (x86)EmbarcaderoStudio21.0binLicenseManager.exe”) and delete any trial or beta (Test Field) license that you can find. Check it under “License Details” in the center column. Under your Control Panel’s Program and Features Add/Remove Program uninstall the following entries: RAD Studio 10.4 version 21.0 Please follow these instructions to remove any leftover files:     If Windows 64-bit, remove the C:Program Files (x86)EmbarcaderoStudio21.0 directory (or the custom folder you had used).    Remove the C:UsersPublicDocumentsEmbarcaderoStudio21.0 directory    Remove the C:ProgramDataEmbarcaderoStudio21.0 directory.    Remove the %APPDATA%EmbarcaderoBDS21.0 directory.    Remove the HKEY_CURRENT_USERSOFTWAREEmbarcaderoBDS21.0 registry key    If Windows 64-bit, remove the HKEY_LOCAL_MACHINESOFTWAREWow6432NodeEmbarcaderoBDS21.0    If Windows 64-bit, remove the following files from C:WindowsSysWOW64:        BDEAdmin.*        CC32*.DLL        Midas.*        Xerces*.DLL Field testers should also do the following (and others may want to as well):     Delete the Godzilla license from License manager before uninstalling it or during the installation of RAD Studio 10.4 Sydney If you had problems in the second step (uninstalling from Windows Control Panel), try this Microsoft tool to solve un-installation problems: http://go.microsoft.com/?linkid=9779673

Earlier we learned how to create a Python type using Delphi classes. How about creating a Python type with some containers or collections capabilities in Delphi and accessing its elements? Python4Delphi PyObject contains Type Services routines e.g Basic, Number, Sequence, Mapping which can be overridden with our custom Python Types Delphi classes. This post helps to do that. Python4Delphi Demo27 Sample App shows how to create a Module, Python type, Import the module, and Python Type in a python script, create a sequence type object and access some of the service routines like length, indexing, etc. You can find the Demo27 source on GitHub. Prerequisites: Download and install the latest Python for your platform. Follow the Python4Delphi installation instructions mentioned here. Alternatively, you can check out this video Getting started with Python4Delphi. Components used in Python4Delphi Demo27 Sample App: TPythonEngine: A collection of relatively low-level routines for communicating with Python, creating Python types in Delphi, etc. It’s a singleton class. TPythonGUIInputOutput: Inherited from TPythonInputOutput (which works as a console for python outputs) Using this component Output property you can associate the Memo component to show the Output. TPythonModule: It’s inherited from TMethodsContainer class allows creating modules by providing a name. You can use routines AddMethod, AddMethodWithKW, AddDelphiMethod, AddDelphiMethodWithKeywords to add a method which should be type compatible with this routine parameter. You can create events using the Events property. TPythonType: This component helps to create a new python type in Delphi which is inherited from the hierarchy of classes (set of APIs to create, manage methods, and members). TMemo: A multiline text editing control, providing text scrolling. The text in the memo control can be edited as a whole or line by line. You can find the Python4Delphi Demo27 sample project from the extracted repository ..Python4DelphiDemosDemo27.dproj. Open this project in RAD Studio 10.4.1 and run the application. Implementation Details: PythonEngine1 provides the connection to Python or rather the Python API. This project uses Python3.9 which can be seen in TPythonEngine DllName property. PythonGUIInputOutput1 provides a conduit for routing input and output between the Graphical User Interface (GUI) and the currentlyexecuting Python script. PythonModule1 with a Module name test is created. In this sample, Created a Delphi class(TMySeq) implementing a new Python type. It is derived from TPyObject. It overrides some Mapping services virtual methods such as MpLength, MpSubscript. function TMySeq.MpLength: NativeInt; begin Result := 10; end; function TMySeq.MpSubscript(obj: PPyObject): PPyObject; begin Result := obj; GetPythonEngine.Py_XINCREF(obj); end; function TMySeq.MpLength: NativeInt; begin   Result := 10; end;   function TMySeq.MpSubscript(obj: PPyObject): PPyObject; begin   Result := obj;   GetPythonEngine.Py_XINCREF(obj); end; During PythonType1 initialization assign the property PyObjectClass with the class TMySeq. procedure TForm1.PythonType1Initialization(Sender: TObject); begin with Sender as TPythonType do PyObjectClass := TMySeq; end; procedure TForm1.PythonType1Initialization(Sender: TObject); begin   with Sender as TPythonType do     PyObjectClass := TMySeq; end; On Clicking Execute Button the below code is executed. procedure TForm1.Button1Click(Sender: TObject); begin PythonEngine1.ExecStrings(Memo2.Lines); end; procedure TForm1.Button1Click(Sender: TObject); begin   PythonEngine1.ExecStrings(Memo2.Lines); end; Which will execute the python script mentioned below. import test S=test.CreateMySeq() print (S) print (len(S)) print (S[1]) print (S[1,2]) print (S[1:2]) print (S[1:20:2]) print (S[…]) print (S[1,4,5:8, 10:20:2, …]) import test S=test.CreateMySeq() print (S) print (len(S)) print (S[1]) print (S[1,2]) print (S[1:2]) print (S[1:20:2]) print (S[…]) print (S[1,4,5:8, 10:20:2, …]) Note. CreateMySeq in the above script is created automatically by Python4Delphi when the property GenerateCreateFunction of TPythonType1(MySeq) is true. Python4Delphi Demo27

import spam   class MyPoint(spam.Point):   def Foo(Self, v):     Self.OffsetBy(v, v)   # old way to create a type instance p = spam.CreatePoint(2, 5) print (p, type(p)) p.OffsetBy( 3, 3 ) print (p.x, p.y) print (“Name =”, p.Name) p.Name = ‘Hello world!’ print (“Name =”, p.Name)   # new way to create a type instance p = spam.Point(2, 5) # no need to use CreateXXX anymore print (p, type(p)) p.OffsetBy( 3, 3 ) print (p.x, p.y)   # create a subtype instance p = MyPoint(2, 5) print (p, type(p)) p.OffsetBy( 3, 3 ) print (p.x, p.y) p.Foo( 4 ) print (p.x, p.y) print (dir(spam)) print (spam.Point) print (“p = “, p, ”  –> “,) if type(p) is spam.Point:   print (“p is a Point”) else:   print (“p is not a point”) p = 2 print (“p = “, p, ”  –> “,) if type(p) is spam.Point:   print (“p is a Point”) else:   print (“p is not a point”) p = spam.CreatePoint(2, 5) try:   print (“raising an error of class EBadPoint”)   p.RaiseError() # it will raise spam.EBadPoint except spam.PointError as what: # this shows you that you can intercept a parent class   print (“Caught an error derived from PointError”)   print (“Error class = “, what.__class__, ”     a =”, what.a, ”   b =”, what.b, ”   c =”, what.c)   # You can raise errors from a Python script too! print (“——————————————————————“) print (“Errors in a Python script”) try:   raise spam.EBadPoint(“this is a test!”) except:   pass   try:   err = spam.EBadPoint()   err.a = 1   err.b = 2   err.c = 3   raise err except spam.PointError as what: # this shows you that you can intercept a parent class   print (“Caught an error derived from PointError”)   print (“Error class = “, what.__class__, ”     a =”, what.a, ”   b =”, what.b, ”   c =”, what.c)   if p == spam.CreatePoint(2, 5):   print (“Equal”) else:   print (“Not equal”)

In this post, you will discover two different demo application, the first one shows you how to add sliding tabs to an application through the use of multiple tabs with custom settings, next and back buttons, and gesture support. The second sample shows you how to implement a master-detail interface and display the Multiview control as a slide-in drawer, popover menu, docked panel, and more. What can you learn? Tab Control Input Form Creation Gestures Animation and managing the form with custom functions You can get these demo application from GetIt! Be sure to check out more sample applications in GetIt here!