Hi how to use foreach loop in managed code c++ using vs2003.
I've never used it, but this MSDN article indicates the general syntax is just:
for each(Type t in IEnumerable)
{
}
Matthew is mostly correct, but here's a working block of code;
///////
array<Type^>^ iterate_me = gcnew array<Type^>(2);
iterate_me[0] = Type::GetType("Type");
iterate_me[1] = Type::GetType("System.Int32");
///////
for each(Type^ t in iterate_me)
Console::WriteLine(t);
The changes were Type is a reference class, so you use "Type^" not "Type" and you need an actual object reference (iterate_me)...
Something like:
String ^ MyString = gcnew String("abcd");
for each ( Char c in MyString )
Console::Write(c);
As of VS2022 for each apparently no longer works. Instead you can do something like this:
IEnumerator^ enumerator = myList->GetEnumerator();
while (enumerator->MoveNext())
{
// Do stuff
}
I don't think that VC++ has foreach
Related
Is there a way to set the context of the expression in Dynamic Expresso library, so that we can do something like the following:
interpreter.Eval("FirstName", new Parameter("person", new { FirstName="Homer", LastName="Simpson"}));
rather than
interpreter.Eval("person.FirstName", new Parameter("person", new { FirstName="Homer", LastName="Simpson"}));
Maybe we could have a another option that would say that the first parameter is to be used as the context for the expression.
I guess there could also be another version of Parse and Eval methods that simply takes the expression text and a simple object value that will serve as the expression context.
Other than that and the lack of support for dynamic types, I am really liking this library. I had worked on something similar, but had not added support for extension methods and generic method calls.
Thanks for the great library,
Neal
There isn't a built-in solution but you can simulate it in many ways:
Option 1: Inject an expression
var workingContext = new { FirstName = "homer" };
var workingContextExpression = Expression.Constant(workingContext);
var firstNameExpression = Expression.Property(workingContextExpression, "FirstName");
var interpreter = new Interpreter();
interpreter.SetExpression("FirstName", firstNameExpression);
Assert.AreEqual(workingContext.FirstName, interpreter.Eval("FirstName"));
Basically I inject an expression using SetExpression method. The injected expression is the property that you want to be available.
Option 2: Use this/me/it variable
You can inject a variable that will contain your working object. I usually call it this (or me or it depending on the application).
var workingContext = new { FirstName = "homer" };
var interpreter = new Interpreter();
interpreter.SetVariable("this", workingContext);
Assert.AreEqual(workingContext.FirstName, interpreter.Eval("this.FirstName"));
Option 3: A combination of the previous solutions
var workingContext = new { FirstName = "homer" };
var interpreter = new Interpreter();
interpreter.SetVariable("this", workingContext);
var firstNameExpression = interpreter.Parse("this.FirstName").LambdaExpression.Body;
interpreter.SetExpression("FirstName", firstNameExpression);
Assert.AreEqual(workingContext.FirstName, interpreter.Eval("FirstName"));
Equal to the first solution but I generate the expression using the parser itself.
Consider that all solutions assume that you must have an Interpreter instance for each context.
Disclaimer: I'm the author of Dynamic Expresso library.
Starting with DynamicExpresso v2.13.0, it's possible to define a variable named "this", that will be used for implicit resolution:
var target = new Interpreter();
target.SetVariable("this", new { FirstName="Homer", LastName="Simpson"});
// 'this' variable is used implicitly
Assert.AreEqual("Homer", target.Eval("FirstName"));
// 'this' variable can also be used explicitly
Assert.AreEqual("Homer", target.Eval("this.FirstName"));
I try to read the plist / xml file which is behind the terminal commando:
defaults read com.apple.dock
I tried NSUserDefaults without success. Maybe you can help me. Thanks.
You can use CFPreferences, for example
CFStringRef orient = (CFStringRef) CFPreferencesCopyAppValue( CFSTR("orientation"), CFSTR("com.apple.dock") );
Boolean hidesIsValid = false;
Boolean hides = CFPreferencesGetAppBooleanValue( CFSTR("autohide"), CFSTR("com.apple.dock"), &hidesIsValid );
While JWWalker's answer that uses CoreFoundation APIs works fine, a more modern way is to use Foundation APIs, like so:
if let defaults = UserDefaults(suiteName: "com.apple.dock") {
let orientation = defaults.string(forKey: "orientation")
let autohide = defaults.bool(forKey: "autohide")
...
}
I'm trying to use vars.put to write the result of the property of an object in a jmeter variable in javascript, but i have an issue...
Here is my code:
eval('var obj = ' + prev.getResponseDataAsString());
var meta_key = vars.get("MetaKey"); //meta_key is a variable
This works fine:
vars.put("content_metakey", obj[meta_key]);
but when i do this, it's doesn't work:
vars.put("taille", obj.meta_key[0].id); //meta_key variable
vars.put("taille", obj.tag[0].id); //tag is the value
Do you have any clue?
Thanks for your help.
i don't know if it's possible, so i used another way to do this: i used another eval.
my code:
obj2 = eval(obj[meta_key]);
vars.put("id_metakey"+meta_type,obj2[0].id);
I try to simply change value of SSIS variable doing this code in ScriptTask:
string path = Dts.Connections["BazyPobrane"].ConnectionString.ToString();
string[] nameZIParray = Directory.GetFiles(path, "*.ZIP");
string[] nameRARarray = Directory.GetFiles(path, "*.RAR");
foreach (string nameZIP in nameZIParray) //search new ZIP
{
if (File.GetCreationTime(nameZIP) > DateTime.Now.AddDays(-1))
{
Dts.Variables["User::NazwaPliku"].Value = Path.GetFileName(nameZIP);
}
}
foreach (string nameRAR in nameRARarray) //search new RAR
{
if (File.GetCreationTime(nameRAR) > DateTime.Now.AddDays(-1))
{
Dts.Variables["User::NazwaPliku"].Value = Path.GetFileName(nameRAR);
}
}
Dts.TaskResult = (int)ScriptResults.Success;
After executing ScriptTask it simply don't change the variable Value. Debug mode seems fine. Maybe i miss some component settings?
Thx!
Some things to check:
Are you sure the variable isn't changing? If you put a subsequent script task with a MessageBox in place, does it show the correct value?
I don't think you need the variable type, i.e. remove "user::"
Make sure the variable is in the ReadWriteVariables property, as suggested by #OcasoP
What's the scope of the variable? Make sure you don't have two copies at different scopes, or that at least the one you do have is visible from the scope of the script
You could try locking the variable before writing to it (which should be equivalent to (3) above)
Code example for the last point:
IDTSVariables100 variables = null;
this.VariableDispenser.LockOneForWrite("NazwaPliku",ref variables);
variables[0].Value = myValue;
variables.Unlock();
debug your script task adding MsgBox(variable_name) and see its value through the execution.
Best debugging option :)
I want to know if it's possible to retrieve the variables name from when it was passed into a certain function. For example, if I call parseId(myId) to a function with the signature parseId(id), i can obviously retrieve the value of 'id'. However, is there any way I can retrieve 'myId' as a string (without passing it as another value)?
Specifically in vb.net, but I'm interested in how it would work in any given language.
This is all just random thoughts.. feel free to dismiss or not ;-p
Re your comment about use with stored procedures... if you want to go that route, I wouldn't mess around with the local variable names; that is an implementation detail. However, you could expose those details on an interface method and use the names from there, since that is more formalised - for example (C#):
interface ICustomerRepository {
Customer GetById(int id); // perhaps an attribute to name the sproc
}
You can use similar expression-tree parsing (as discussed here) to get the name and value of the parameter, for example:
var repoWrapper = new Repo<ICustomerRepository>();
int custId = 12345;
var cust = repoWrapper.Execute(r => r.GetById(custId));
Here we'd want to resolve the argument to GetById as "id" (not "custId"), with value 12345. This is actually exactly what my protobuf-net RPC code does ;-p (just don't ask me to translate it to VB - it is hard enough to write it in a language you know well...)
No, you can't do that in the normal sense. What are you really trying to accomplish with this?
You can do this in .NET 3.5 and above using expression trees; I'll knock up a C# example, and try to run it through reflector for VB...
C#:
static void Main()
{
int i = 17;
WriteLine(() => i);
}
static void WriteLine<T>(Expression<Func<T>> expression)
{
string name;
switch (expression.Body.NodeType)
{
case ExpressionType.MemberAccess:
name = ((MemberExpression)expression.Body).Member.Name;
break;
default:
throw new NotSupportedException("Give me a chance!");
}
T val = expression.Compile()();
Console.WriteLine(name + "=" + val);
}
The VB is below, but note that the VB compiler seems to use different names (like $VB$Local_i, not i):
Sub Main()
Dim i As Integer = 17
WriteLine(Function() i)
End Sub
Private Sub WriteLine(Of T)(ByVal expression As Expression(Of Func(Of T)))
If (expression.Body.NodeType <> ExpressionType.MemberAccess) Then
Throw New NotSupportedException("Give me a chance!")
End If
Console.WriteLine((DirectCast(expression.Body, MemberExpression).Member.Name
& "=" & Convert.ToString(expression.Compile.Invoke)))
End Sub