I have a class which contains a field that has an array of eltTypes. This looks like this:
type eltType;
var size = 5;
var elementsDomain: domain(1) = {0..size-1};
var elements: [elementsDomain] eltType;
Later on, I have a method that utilizes this (still inside of the class) like this:
proc add(eltType el){
elements[0] = el;
}
I get a compiler error that says it has a syntax error at the add method signature. I thought eltTypes worked like generic types in java. How exactly am I doing eltTypes wrong, and how are they supposed to work?
You need to declare the type of el in the following format:
proc add(el : eltType) {
Chapel does a good job of figuring out types (except for fruitful recursive functions) so it should also work if you leave the type out and say:
proc add(el) {
Related
I'd like to use something like the "Concepts" package from Atila Neves.
I implemented the check of an object against a type signature myself in a simple naive way. I can check struct objects against interfaces which I define within compile-time-evaluated delegate blocks to make them work with BetterC. I only used compile-time function evaluation with enums which receive return values of executed delegate code blocks.
Now I faced problems with std.format.format which uses TypeInfo for %s formatters which gives errors when compiling in BetterC. For code generation I'd like to use token strings because they have syntax highlighting. But proper usage of them requires string interpolation or string formatting. core.stdc.stdio.snprintf is no alternative because CTFE can only interprete D source code.
This is not technically a problem. I can just turn token strings into WYSIWYG strings.
But I wonder why I can't use it. The official documentation says, compile-time features are unrestricted for BetterC (I assume this includes TypeInfo). Either it is plain wrong or I am doing it wrong.
template implementsType(alias symbol, type)
if (isAbstractClass!type)
{
enum implementsType = mixin(implementsTypeExpr);
enum implementsTypeExpr =
{
import std.format : format;
auto result = "";
static foreach(memberName; __traits(allMembers, type))
{
result ~= format(
q{__traits(compiles, __traits(getMember, symbol, "%1$s")) && }~
q{covariantSignature!(__traits(getMember, symbol, "%1$s"), __traits(getMember, type, "%1$s")) && }
, memberName);
}
return (result.length >= 3)? result[0 .. $-3] : result;
}();
}
TypeInfo are not available with BetterC.
There's a bc-string dub package that provides a limited string formatter that will work in BetterC.
I'm not going to get into too much of the details on the Excel side of things, I essentially took code from this example:
C++ app automates Excel (CppAutomateExcel)
solution1.cpp
So I've tried this code in MSVC and it compiles:
class foo { public: virtual void bar(){} };
int main()
{
void (foo::*p)() = &foo::bar;
}
But similar code to capture the address of the move function in Excel does not work:
int main()
{
Excel::_ApplicationPtr spXlApp;
HRESULT hr = spXlApp.CreateInstance(__uuidof(Excel::Application));
Excel::WorkbooksPtr spXlBooks = spXlApp->Workbooks;
Excel::_WorkbookPtr spXlBook = spXlBooks->Add();
Excel::_WorksheetPtr spXlSheet = spXlBook->ActiveSheet;
HRESULT(Excel::_Worksheet::*pMove)(...) = &spXlSheet->Excel::_Worksheet::Move;
<... irrelevant code ...>
return 0;
}
This has the following compiler error:
error C2276: '&': illegal operation on bound member function expression
If I remove the &, it says I should add it back:
error C3867: 'Excel::_Worksheet::Move': non-standard syntax; use '&' to create a pointer to member
Any help on what to do here would be greatly appreciated.
You say in your question "but similar code..." and then you show code in which you do not do the same thing. Try using the same syntax for setting pMove as you used for setting p in your smaller example. Try something like &Excel::_Worksheet::Move; (without the "spXlSheet->").
If you can specify the specific instance of the object for which to call the function pointer at the time that you set the function pointer as you have there, I'm not aware of such a capability. After dropping spXlSheet-> from where you set the variable, use it instead where you want to call the function pointer.
You need to declare the method pointer like this instead:
// or whatever parameter type Move() actually uses...
void (Excel::_Worksheet::*pMove)(tagVARIANT, tagVARIANT) = &Excel::_Worksheet::Move;
Then, to actually call pMove(), you would have to do something like this:
Excel::_WorksheetPtr spXlSheet = ...;
(spXlSheet.Get()->*pMove)(...);
I have a data structure defined up here called this:
typedef list <classSpec*> ClassSpecList;
I'm trying to add stuff into the list here based on functions that return certain values of that match the same data type. In one function, I have a list pointer object defined here and I have another statement that calls a function.
ClassSpecList *answer = 0;
classSpec *thisanswer = parseClass(br);
Basically I'm trying to add the results of what thisanswer returns into my main ClassSpecList. Problem is, when I try
answer->push_back(new classSpec (*thisanswer));
It compiles but I get a seg fault
When I try somethign else like:
answer->insert(ClassSpecList.begin(), *thisanswer);
I keep getting primary expression errors and I do not know why. I even tried it with other list made without typedef and I still get those.
Thank you.
You should initialize the pointer answer first, like :
ClassSpecList *answer = new ClassSpecList;
then you can add thisAnswer into this list.
This should work:
ClassSpecList *answer = new ClassSpecList;
answer->push_back(thisAnswer);
as should this, which is usually recommended:
ClassSpecList answer;
answer.push_back(thisAnswer);
If possible, parseClass shouldn't return a pointer, and you should use typedef list <classSpec> ClassSpecList;.
I am coming from the C++ world and i want to do some simple stuff with Actionscript 3.0.
Have search around this site and google and haven't found a universally accepted way to do so. I will give you the C++ code of the analogous of what I am trying to do in Actionscript 3.0.
Pass by reference:
void somefunction (string &passvariable);
Create instance of, deep copy:
string something;
string somethingelse;
something = "randomtext";
somethingelse = something;
Pass by reference
Every object is passed by reference. As far as I know, there are no explicit & address of or * dereference operators. Actionscript is a higher level language than that.
Primitive types (and Strings are primitive - see link) are Immutable in Actionscript, so pass by value / pass by reference are effectively the same.
Deep Copy / Instance of
ObjectUtil.clone / ObjectUtil.copy will create sometimes-deep copies of Objects, if you're working in Flex. I usually don't rely on it for anything deep, however. In most cases you will want to create your own clone style method to create a deep copy.
A generic, flexible clone method can be found here
The rules for pass as reference are different for simple data types like string and number than they are for objects and complex data types.
If you are passing a string to a function, it creates a copy, leaving the original untouched.
So to pass by reference, try creating an object:
var str:Object = {string:"foo"};
passByref(str);
trace(str.string);
private function passByref(str:Object):void
{
str.string = str.string + "bar";
trace("inside", str);
}
As for deep object cloning, this works great:
package
{
import flash.utils.ByteArray;
public class DeepCopyUtil
{
public static function clone (source : Object) : *
{
var array : ByteArray = new ByteArray ();
array.writeObject (source);
array.position = 0;
return array.readObject ();
}
}
}
Credit where credit is due:
http://cookbooks.adobe.com/post_How_to_create_deep_copies_of_objects_and_arrays-19261.html
In Actionscript you have to define all things with function, var or const.
You should define the (return type) after the variable name, like var:String
Creating a function
function someFunction (var:String):void
{
}
Copy a string
var something:String;
var somethingElse:String;
something = "randomtext";
somethingelse = something;
I'm a newbie at using the STL Algorithms and am currently stuck on a syntax error. My overall goal of this is to filter the source list like you would using Linq in c#. There may be other ways to do this in C++, but I need to understand how to use algorithms.
My user-defined function object to use as my function adapter is
struct is_Selected_Source : public std::binary_function<SOURCE_DATA *, SOURCE_TYPE, bool>
{
bool operator()(SOURCE_DATA * test, SOURCE_TYPE ref)const
{
if (ref == SOURCE_All)
return true;
return test->Value == ref;
}
};
And in my main program, I'm using as follows -
typedef std::list<SOURCE_DATA *> LIST;
LIST; *localList = new LIST;;
LIST* msg = GLOBAL_DATA->MessageList;
SOURCE_TYPE _filter_Msgs_Source = SOURCE_TYPE::SOURCE_All;
std::remove_copy(msg->begin(), msg->end(), localList->begin(),
std::bind1st(is_Selected_Source<SOURCE_DATA*, SOURCE_TYPE>(), _filter_Msgs_Source));
What I'm getting the following error in Rad Studio 2010. The error means "Your source file used a typedef symbol where a variable should appear in an expression. "
"E2108 Improper use of typedef 'is_Selected_Source'"
Edit -
After doing more experimentation in VS2010, which has better compiler diagnostics, I found the problem is that the definition of remove_copy only allows uniary functions. I change the function to uniary and got it to work.
(This is only relevant if you didn't accidentally omit some of your code from the question, and may not address the exact problem you're having)
You're using is_Selected_Source as a template even though you didn't define it as one. The last line in the 2nd code snippet should read std::bind1st(is_Selected_Source()...
Or perhaps you did want to use it as a template, in which case you need to add a template declaration to the struct.
template<typename SOURCE_DATA, typename SOURCE_TYPE>
struct is_Selected_Source : public std::binary_function<SOURCE_DATA *, SOURCE_TYPE, bool>
{
// ...
};
At a guess (though it's only a guess) the problem is that std::remove_copy expects a value, but you're supplying a predicate. To use a predicate, you want to use std::remove_copy_if (and then you'll want to heed #Cogwheel's answer).
I'd also note that:
LIST; *localList = new LIST;;
Looks wrong -- I'd guess you intended:
LIST *locallist = new LIST;
instead.