Manage separate parser contexts for different application modules.

ID: 271

See: DefaultCount = [int], DefaultInstance = [uCalc], Introduction, IsDefault = [bool] 
				
					using uCalcSoftware;

var uc = new uCalc();
// --- Main Application Context ---
// Starting with the 'uc' object as the initial default.
uCalc.DefaultInstance.DefineConstant("PI = 3.14159");
Console.WriteLine($"Initial Count: {uCalc.DefaultCount}");

// --- A Plugin needs a temporary, isolated context ---
using (var moduleCalc = new uCalc()) {
   moduleCalc.IsDefault = true; // Push the new instance onto the stack.
   Console.WriteLine($"Count after module pushes new default: {uCalc.DefaultCount}");

   // The module's context is now active.
   // uCalc::DefaultInstance() would now return 'moduleCalc'.
}

// When 'moduleCalc' goes out of scope, it's destroyed and automatically
// removed from the stack, restoring the previous default.

Console.WriteLine($"Count after module instance is disposed: {uCalc.DefaultCount}");

// Verify the original default instance is active again.
var result = uCalc.DefaultInstance.EvalStr("PI");
Console.WriteLine($"Original context restored. PI = {result}");
				
			
Initial Count: 1
Count after module pushes new default: 2
Count after module instance is disposed: 1
Original context restored. PI = 3.14159
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					#include <iostream>
#include "uCalc.h"

using namespace std;
using namespace uCalcSoftware;

int main() {
   uCalc uc;
   // --- Main Application Context ---
   // Starting with the 'uc' object as the initial default.
   uCalc::DefaultInstance().DefineConstant("PI = 3.14159");
   cout << "Initial Count: " << uCalc::DefaultCount() << endl;

   // --- A Plugin needs a temporary, isolated context ---
   {
      uCalc moduleCalc;
      moduleCalc.Owned(); // Causes moduleCalc to be released when it goes out of scope
      moduleCalc.IsDefault(true); // Push the new instance onto the stack.
      cout << "Count after module pushes new default: " << uCalc::DefaultCount() << endl;

      // The module's context is now active.
      // uCalc::DefaultInstance() would now return 'moduleCalc'.
   }

   // When 'moduleCalc' goes out of scope, it's destroyed and automatically
   // removed from the stack, restoring the previous default.

   cout << "Count after module instance is disposed: " << uCalc::DefaultCount() << endl;

   // Verify the original default instance is active again.
   auto result = uCalc::DefaultInstance().EvalStr("PI");
   cout << "Original context restored. PI = " << result << endl;
}
				
			
Initial Count: 1
Count after module pushes new default: 2
Count after module instance is disposed: 1
Original context restored. PI = 3.14159
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					Imports System
Imports uCalcSoftware
Public Module Program
   Public Sub Main()
      Dim uc As New uCalc()
      '// --- Main Application Context ---
      '// Starting with the 'uc' object as the initial default.
      uCalc.DefaultInstance.DefineConstant("PI = 3.14159")
      Console.WriteLine($"Initial Count: {uCalc.DefaultCount}")
      
      '// --- A Plugin needs a temporary, isolated context ---
      Using moduleCalc As New uCalc()
         moduleCalc.IsDefault = true '// Push the new instance onto the stack.
         Console.WriteLine($"Count after module pushes new default: {uCalc.DefaultCount}")
         
         '// The module's context is now active.
         '// uCalc::DefaultInstance() would now return 'moduleCalc'.
      End Using
      
      '// When 'moduleCalc' goes out of scope, it's destroyed and automatically
      '// removed from the stack, restoring the previous default.
      
      Console.WriteLine($"Count after module instance is disposed: {uCalc.DefaultCount}")
      
      '// Verify the original default instance is active again.
      Dim result = uCalc.DefaultInstance.EvalStr("PI")
      Console.WriteLine($"Original context restored. PI = {result}")
   End Sub
End Module
				
			
Initial Count: 1
Count after module pushes new default: 2
Count after module instance is disposed: 1
Original context restored. PI = 3.14159
Explore 600+ other examples