Is it the best override for Equals (in VB.NET) for an object having an unique ID? [code]I took that example from the MSDN, but not entirely sure if from all points of view (including performance) is the better solution.[code]
View 2 Replieswhen I was a comparitive novice to the novice I am right now, I used to think that these two things were syntactic sugar for each other, ie. that using one over the other was simply a personal preference. Over time, I'm come to find that these two are not the same thing, even in a default implementation (see this and this). To further confuse the matter, each can be overriden/overloaded seperately to have completely different meanings.
View 6 RepliesI implemented a PagedModel class to wrap around IEnumerable to provide paging data for grids in my MVC app.I used Resharper's auto-generated Equality code telling it to check the data, total rows, page number, and page size fields.[code]I found the call to Equals(other._ModelData, _ModelData) peculiar, as AFAIK, this checks that it is the same object rather than that the contained items are the same. Because my tests were failing anyways, I went ahead and changed it to other._ModelData.Equals(_ModelData) with no success. Then I reflected into it at debug time and found that other._ ModelData.GetType().GetMethod("Equals",{GetType(Object)}).DeclaringType was Object! Obviously, that would result in the failed comparison.I came up with a solution to create a EnumerableEquals method which compares every item in the two enumerables to confirm the are the same, but it seems sloppy. Is there anything I can do to use the normal .Equals method? [code]
View 2 RepliesI am comapring 2 contract IDs, one is sent by the caller, the other is in a file and read into a variable. I use a string.Equals method to compare the contract IDs. The contract IDs compare successfully if the number in a contract ID is more than 1 away from the the other for example:
CTSRG0006 & CTSRG0005 = false
However
CTSRG0006 & CTSRG0007 = true
the code I am using for the comparison:
If fileContractID.Equals(calledContractID) Then
isFileValid = True
End If
I'm making a sort of VB.NET calculator that has all of the advanced features. I would also like it to have programming-style tips so that I won't have to build in things like ABS and EQUALS.
For example, ABS is sqrt(x ^ 2) and EQUALS is NOT(OZ(x-y)). NOT is 1 - OZ(x).
(x and y are the variables.)
I've come up with a few, but many rely on OZ(). OZ stands for 1/0. I need a formula that will return 1 if the value is <> 0, but 0 if it is equal to 0. I've worked on this for days but I can't come up with anything. Does anyone know how to do this?
i read it on internet article already, and tested it already. but it didnt show any difference.
View 3 RepliesIn code, why wouldn't this work? intMax = intTopValue = 20
View 2 RepliesWhat is the difference between Equals and = in LINQ?
Dim list As List(Of Foo) = (From a As Foo In FooList _
Join b As Bar In BarList _
On a.Something = b.Something _
Select a).ToList()
versus Dim list As List(Of Foo) = (From a As Foo In FooList _Join b As Bar In BarList _On a.Something Equals b.Something _Select a).ToList()
I have three classes which implement an Interface iComparesWith, and I wish there to be a single function such that each iComparesWith object of any of the three implementing classes should be able to compare itself with any other iComparesWith object, again, of any of the three implementing classes, and know if the two objects are equal. How can I code this so that the comparison code is only written once? Is it the case that I will have to create a top-level MustInherit class which implements the equality comparison, and have MustOverride methods for all of the methods of iComparesWith?
View 1 RepliesIn code, why wouldn't this work?
intMax = intTopValue = 20
I stumbled upon an article regarding the Birthday Paradox and it's implications when overriding the GetHashCode method, I find myself in a bind.In tests, we found that in calls to the ToLookup() Extension, only GetHashcode is used, despite providing the implementation for Equals.
I think I understand why this happens, the internal working of ToLookup, HashSet, Dictionary, etc, use the HashCodes to store and/or index their elements?Is there a way to somehow provide the functionality so that the equality comparison is actual performed using the equals method? Or should I not be concerned with the collisions? I haven't done the maths myself, but according to the first article I linked, you would only need 77,163 elements in a list before reaching a 50% chance of collision.
If I understand this correctly, an Equals() override that compares property by property such as
Return (a.Property1 == b.Property1 && a.Property2 == b.Property2 && ...)
should have a zero chance of collision? So how can I get my ToLookup() to equality compare this way?
In case you need an example of what I mean:
[Code]...
I can get that to work with an override of GetHashcode(), no problems. But I don't want to use GetHashcode because if I have, for example, 109,125 elements in my list, apparently I'm already at 75% chance of collision? If it used aforementioned Equals() override, I think I'd be at 0%?
Well I thought this was going to be easy, then the problem showed up.So I have a structure defined, as follows:
Structure Testing
Dim i as short
Dim j() as short
[code]....
And I need to do the same with all of the T2 array members.Now I get into writing the real code. Something like this:
For i = 1 to 100
Populate portions of T1 'not all values of T1 are used for each value of i
T2(i) = T1
Reset T1 to zero values and empty strings
Next i
So what is going wrong? After I set my T1 components back to zero, my T2(i).j has had all its 1-10 index values set to zero. Note that it is just the array, not the string s or the non-array i.Sure, I could write some code where I set T2(i).i = T1.i, and so on for each variable in the structure. But I have a feeling that is not the right way. There is some kind of equivalence going on between T2(i) and T1 in each loop. And I would would like to understand that more so I know how to really deal with it.
Is there a way to translate this code in VB? Most of it is easy, but I can't figure out a way to override the event handler.
public class MTObservableCollection<T> : ObservableCollection<T>
{
public MTObservableCollection()
{
[code]....
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
Try
If disposing = true And components IsNot Nothing Then
components.Dispose()
End If
Finally
MyBase.Dispose(disposing)
End Try
End Sub
Error: Protected Overrides Sub Dispose(disposing As Boolean)' has multiple definitions with identical signatures.How can I call this without raising an error ?
Simple question but it is killing.
How do I write an expression, that return the number of rows where a column is equal something.
I can get the total rows like this: =Count(Fields!Foo.Value) and RowNumber("Rapporter")
But I can't get the number of rows where Foo is equal to someString
Foo is a type string.
I have a structure written in vb.net with all shared members. I need to override 'Equals', '==' and '!=' to avoid a warning.
View 4 RepliesI just ran into what I consider a very strange issue in the execution of some code that I thought I had completely well-understood.
Basically, I was using this kind of notation:
If strOne.equals(strTwo) Then
rather than
If strOne = strTwo Then
I came from a c and java background, and using the '=' operator for comparison has always made me cringe, so I've used the .equals() comparison function thinking that it was equivalent. But just now some of my code broke. It encountered a string containing "Eagle's Nest: Dawn Patrol", used the .equals() to compare it to "Eagle's Nest: Dawn Patrol" and declared them not equal. I changed the code to use '=' rather than '.equals()' and it declared them equal. I also did this:
If strOne.Replace("'", "").Equals(strTwo.Replace("'", "")) Then
And again, it declared them equal.
This has me a little rattled because my code is filled with the use of .equals(), and I've used it assuming that it was no different than writing strOne = strTwo. I've scanned the interweb looking for information about this. I have not found any information about odd interactions between the apostrophe (or other) character(s) and .equals(). Microsoft's documentation does not hint at any subtle differences. how .equals() differs from '='
I am trying to filter a dataset by adding together numbers within a specified field (say field1) within the dataset until i reach a specified number.
The filtered dataset should either be precisley equal to the number or most likley less than. In short if a row exceeds the number it should revert to the previous record.
I have no probs with general filtering and using data adapters to access the data. But im struggerling with the loop side of things.
[code]Where I add my parameter, I am trying to have it pull records that contain the text that is in the jpDescTextBox instead of being exactly equal to it. I have tried using wildcards such as * and %.
View 7 RepliesSome of my DataGridViewCells return the wrong value in their GetClipboardContent method. They are cells in a DataGridViewComboBoxColumn cells, so they use the displayed property, not the value property of the cell. I want it to return the value itself.An initial attempt was simply using
Protected Overrides Function GetClipboardContent(ByVal rowIndex As Integer, ByVal firstCell As Boolean, ByVal lastCell As Boolean, ByVal inFirstRow As Boolean, ByVal inLastRow As Boolean, ByVal format As String) As Object Return Value End Function in my DataGridViewComboBoxCell descendant but then I noted that this method is called more than one time per cell value, once for every data format DataGridView supports by standard, which are format="HTML", "Text", "UnicodeText" and "Csv". For csv, the base implementation appends a comma if it's not the last cell, for html it adds the correct tags depending on if it's the first/last row/cell in the table/table row, etc. I consider this format-specific, not cell-value specific.
So how could I replace the value that ends up in the clipboard without re-implementing all those format-specific aspects? That would result in quite some code for functionality that already exists in the base class, wouldn't it?
I have a theoretical class Name_Order, that has a string Name and a int Order. I need to indicate that two Name_Order's are different, if the pair NameOrder is different, that is, or name or order are different. Now, overriding Equals no problemo, but I have some "issues" with GetHashCode:
[Code]...
I have a main class that has a Sub procedure with no implementation. Any derived class should override and implement this procedure, so I used MustOverride in the base class.
Now, any time this procedure is called, I need to set a specific Boolean variable to True at the beginning of the procedure and set it to False at the end.
Is there a way to avoid writing these two lines of code in procedure implementation of every single derived class? Can I set this value to True in the base class, then run procedure in the derived class and then set the value back in the base class?
I am setting my viewmodel as datacontext in my xaml but I override it to my view to make few functions work however to achieve the visibility on some grids and I have a property in my VM can I override my datacontext back to my VM? If so how? I have a stackpanel that has datacontext overriden as my grid and within that stackpanel I need to change the datacontext for a button.
View 1 RepliesI inherited DataGridViewTextBoxCell because I need to add some custom property to it.
At run-time after creating the DataGridView instance and bind the data I do the following:
For k As Integer = 0 To grid.Columns.Count - 1
grid.Columns(k).AutoSizeMode = DataGridViewAutoSizeColumnMode.ColumnHeader
If k > 0 Then grid.Columns(k).CellTemplate = New CustomCell()
Next
[Code]....
the cell type is never of type CustomCell but it remains DataGridViewTextBoxCell.
I know how to handle overriding form closing with FormClosing event and MessageBox prompt by setting e.cancel to true but how can I override deactivation of the mdi child form?
View 3 RepliesI have a DataViewGrid that is populated with emp records sorted by a 'header' record listing the managers name. Currently, the user is a ble to select any row, even the manager row. I want to modify the program to prevent users from being able to select the manager record or 'header' record
View 9 RepliesI have an access database for steel members. Each table has a different type of member, and then in those tables, each size of that member type.
I am about to create a tool that draws these sections when they are selected, but as there are 12 different member types, I don't really want to have 12 different Subs for "Draw" that essentially do the same thing.
I considered polymorphism.. (I think I have it correct)
[code...]
I've got the hang of using dates now, but I haven't learned how to test multiple results of a query. I can return a value from a query, but I'm unsure how to return many without putting them into a data grid view or an object on the form. (In Visual Basic)I have to check when a particular investment needs to be bought or sold, there will be more than one in almost every case. I've got the function to find out the interval between the months, checking if the asset is bought or sold in month x, but I'm unsure how to test it against multiple assets at once - nor do I know the best way to do so.
View 12 RepliesI have a DGV with the Alternating row color set to grey.In the CellFormatting event on the DGV I want to go through the rows as if a cell contains a certain value I want to set the BackColor to red.However when I do this, it just gets overridden with the Alternating grey color. The cell in question in a normal colored row appears in red as expected, just not the alternating row.
rticularly when creating jQuery buttons with no text and just icons) as a result of this.Secondly I am attempting to create my own custom button output by overriding the Render() event and am having a bit of difficulty trying to understand how to go about changing the output that is provided by this event.If I look at the HtmlTextWriter that is provided as the parameter to the Render() event I can see it contains a protected property TagKey = Input {47}, is it possible to simply modify this property somehow and change it to a Button or do I need to create a new instance of the HtmlTextWriter and populate it all from the start? If so, could anyone provide some guidance as to how this would typically be done and if there are any special considerations I need to make to ensure that my derived button class is functionally equivalent to the original (excluding the html)?
<Assembly: TagPrefix("MyCompany", "MyCustomButton")>
Public Class MyButton
Inherits Button
[code].....