I have the following code, whereby I have declared an array or records as Member, the Member type consists of 3 entries, forename, surname and distance. I've tried many variations on my 'call' function but I keep getting the same error:
Here is a shortened format of my 'whole' code, hoping someone can point out whatever silly mistake I'm making here, I can only assume something within the parameter passing or declaration of the record structure?
Hope you can help with my school project.
Just like the message says. You're using a private type, and so it can't be coerced to Variant.
You probably want your Read_In_File Sub to instead declare the type of the parameter, rather than using the default Variant type.
Private Sub Read_In_File(ByRef Members As Member())
Though it's very odd to both have a global variable in your class and a parameter of the same name; so I'm not quite sure what exactly you're trying to accomplish.
The error message is telling you exactly how to solve your issue:
"Only user-defined types defined in public modules can be coerced to or from a variant passed to late-bound functions"
Add a Module to your project called MUserDefinedTypes or modUserDefinedTypes (or whatever naming convention you use) and declare your public user-defined type there.
I also agree with Peter in that you have some funny naming conventions in you code. Do not name your variables the same as you modules, classes, forms, or types. It will only get you into trouble. I suggest a simple prefix approach.
Related
I just discovered that it's apparently not possible to declare a public array in a VBA class while it is fine to declare it private.
I am wondering if this is has a technical reason or if this is a design choice on Microsoft's part.
Either explanation doesn't make much sense to me: I cannot see a technical reason that would prevent a member to be private while it can be public as this is only an access check that is checked at runtime.
On the other hand, I don't understand why it shouldn't be possible to declare public arrays while it is perfectly fine to declare public integers or other data types.
I'd appreciate if someone could explain the rational behind all this.
I believe you'd need to ask the persons who created the Visual Basic (or maybe even Basic) programming language as to "why". It seems to be inherent to the languages. As far as VBA goes, the restriction comes from VB6, on which VBA bases. I find this reference in a Google search:
Declaring data as Public in a Form means you are creating a Property
on that Form, using abbreviated syntax. A Property cannot be an array
using that shortcut syntax.
To say this another way, "Public" only means "global" for
old-fashioned static (BAS) modules. For everything else Public means
something entirely different.
And this:
Instead of Arrays, You can use Collection object or Your own
Collection Class. VB6 does not allow to declare Constants, Arrays,
User Defined Types as Public.
From the VBA Help topic Constants, fixed-length strings, arrays, user-defined types, and Declare statements not allowed as Public members of an object module
Not all variables in an object module can be declared as Public.
However, procedures are Public by default, and Property procedures can
be used to simulate variables syntactically. This error has the
following causes and solutions:
Concerning arrays, specifically
You declared a Public array in an object module. Although a procedure
can't return an array, it can return a Variant that contains an array.
To simulate a Public array in a class module, use a set of Property
procedures that accept and return a Variant containing an array.
I'm trying to create an array of Regex objects, like so: Regex[] regexes;.
The compilation fails with main.d(46): Error: template std.regex.Regex(Char) is used as a type.
I find the documentation cryptic. All I understand is that templates generate code on compilation, but I don't see what's preventing me from creating an array of Regex.
There's an existing question on StackOverflow with the same problem, but it deals with C++, not D.
You cannot create a regex object without first instantiating the template with a type. this is because the actual type is generated at compile time based on the instantiation type you give. Regex itself is not an actual type, it is just a template function allowing you to generate a type when instantiated.
In this case you probably want to change:
Regex[] regexes;
into:
Regex!char[] regexes;
to tell the compiler that your regex contains chars as opposed to some derived type. This means specifically you are instantiating the Regex template with the type char.
As in title I would like to pass an array to the sub which is executed by a button (That's why I don't know ho to pass it to the sub). Array is calculated in the Sheet before you can exectue sub with the button.
I've tried using:
Option Explicit On
Public My_array(1 to 10)
But I have received an error that I can not do that command with array, const etc.
What is the correct way to do it?
I think there is some terminology we can try to clear up: you're not actually passing the variable to the button's procedure. A publicly scoped variable is going to be available within that procedure and does not need to be "passed".
Note: I'm not sure what you mean by "Array is calculated in the Sheet". Unless you are using some event procedure to calculate an array in memory (probably you are not, because you don't have the array scoped or declared properly to do this...), this statement can't possibly be true.
Your declaration should be like:
Public myArray(1 To 10) As Variant 'or As String, As Double, etc.
You can omit the As ... part and it will be type Variant. if you need more strongly-typed array, then you will need to specify.
Also, On is not a legal keyword after the Option Explict statement. So, remove that. But keep Option Explicit in all of your modules.
The error message you receive hints at the solution: You can't put public declarations in object modules. An object module is a Worksheet, Workbook, UserForm, or Class module in the VBE.
You can only put these declarations in a normal code module.
Solution: Move the declaration of myArray to a normal code module.
Let's say I have a generic vector library. To make it easier to use, I want to instantiate various common forms of the vector library and make them visible in a single package.
I'm trying this:
with GenericVector;
package Vectors is
package Vectors3 is new GenericVector(3);
use all type Vectors3.Vector;
subtype Vector3 is Vectors3.Vector;
package Vectors4 is new GenericVector(4);
use all type Vectors4.Vector;
subtype Vector4 is Vectors4.Vector;
end;
The end goal is that I want to be able to do with Vectors; use Vectors; and end up with Vector3 and Vector4 types directly available which Just Work.
Naturally, the code above doesn't work. It looks like the use all type statements import the definitions attached to the specified type into the package specification but then those definitions aren't exported to the user of Vectors. I have to do with Vectors; use Vectors; use all type Vectors.Vectors3; instead. This is kind of sucky.
How can I do this?
You could simply make Vector3 and Vector4 new types, and not just subtypes. That would implicitly declare all the inherited, primitive operations from GenericVector in Vectors.
use Vectors gives you direct visibility to those identifiers that are declared in Vectors, including those that are declared implicitly. (Implicit declarations are things like "+", "-", operators when you declare a new integer type, and inherited operations when you declare a derived type.) But it doesn't give you direct visibility to anything else. In particular, use is not transitive, because use all type Vectors3.Vector does not declare any new identifiers in Vectors.
You could accomplish this by declaring renaming identifiers for everything that you want a use Vectors user to see. (For types, you'd have to use subtype since there's no type renaming in Ada.) E.g. in Vectors:
function Dot_Product (V1, V2 : Vectors3.Vector) return Float
renames Vectors3.Dot_Product;
(I'm just guessing at what the operations in GenericVectors might look like.) Now, anywhere that says use Vectors will be able to use Dot_Product directly. You'd have to do something like this for every identifier, though. If there are a lot of them, this probably isn't a viable solution. (The renaming declaration doesn't have to use the same name Dot_Product.)
Although it may seem annoying that you can't get this kind of transitive visibility, the alternative probably would turn out to be more annoying, because you can't look at Vectors and see what identifiers would be made visible by use Vectors; the result would probably be either unexpected name conflicts or other surprises.
I'm trying to define a generic class that takes a parameterized type T and then use the type in an Array definition in the class. I wrote the following which I thought seemed like it should work
class MyClass[T] {
val myarr:Array[T] = new Array[T](10)
}
But the compiler complains with the following
can't find the class manifest for element type T
value newArray is not a member of Null
Anyone know whats going on here and what its not happy about?
The compiler needs to know how to instantiate things of type T. In the traditional Java way of handling generics through type erasure, this cannot reasonably be done; the compiler just says, "Hey, I don't know what T is, so I don't feel so great about allowing you to instantiate a T like that." In Scala, however, there is a word-around for this: manifests. In order to include the manifest for T, just change the first line of that code to
class MyClass[T : Manifest] {
That's it.