GUI Editor Test Page - MFSD knowledge base

Page

Edit (Text)=20

Info=20

Subscribe=20

Add=20 Link=20

Attachments=20

GUI=20 Editor Test Page

Coding Standards for .NET = using=20 VB Author : Paul RussellDate : Nov 28th=20 2005Reference : MFSD_DOCS_93496_1Version : 1Revision : 1Status : Draft = Summary=20 : The purpose of this document is to present a set of common rules and = recommendations for developing applications using Microsoft VB.NET. By = defining guidelines, an ISTD consistency of style, formatting and = convention=20 can be applied to each new project making development and post = implementation=20 support simpler. This document is based on MSD_DOCS_116811_2 (Coding = Standards=20 for .NET using C#).

AMENDMENTS HISTORY=20 ||Version||<^width=3D"84px"sty= le=3D"BORDER-RIGHT:=20 #ece9d8; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; = PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 63pt; PADDING-TOP: = 0in;=20 BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR:=20 transparent">Revision||<^width=3D"96px"style=3D"BO= RDER-RIGHT:=20 #ece9d8; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; = PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 1in; PADDING-TOP: 0in; = BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent">Edited = By||<^width=3D"309px"style=3D"BORDER-RIGHT: #ece9d8; = PADDING-RIGHT:=20 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in;=20 BORDER-LEFT: #ece9d8; WIDTH: 231.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: = #ece9d8;=20 BACKGROUND-COLOR: transparent">Comment||

Paul Russell

Initial Draft =E2=80=93 based on MSD_DOCS_116811_2 (v2.0) =

Paul Russell

Edited of examples for consistency.Corrections for VB.NET 2005=20 content.Changed text of hyperlinks to display friendly description = instead=20 of URL.

TABLE OF CONTENTS 1.=20 INTRODUCTION. 4 2.=20 DOCUMENT CONVENTIONS. 4 3.=20 NAMING CONVENTIONS. 4 4.=20 APPLICATION OF NAMING CONVENTIONS. 6 5.=20 CODE STYLE. 9 6.=20 CODE COMMENTING. 10 7.=20 CODING GUIDELINES. 11 7.1=20 General11 7.2=20 Variables and Types11 7.3=20 Flow Control11 7.4=20 Exception Handling. 12 7.5=20 Object Composition. 13 7.6=20 Events and Delegates15 7.7=20 Threading. 15

The intention of this document is to describe a set = of=20 standards and guidelines that are to be used for new development = projects using=20 Microsoft VB.NET. These represent a combination of general best practice = coding=20 styles and the conventions used by Microsoft. The goal of the standard = is to=20 make development and support of VB.NET systems simpler and more = consistent=20 across projects. The standard is not complete in the sense that all = standards=20 documents should evolve with experience and changes in the technology. = It is not=20 anticipated that these guidelines will be retrospectively applied to = existing=20 systems. It is the responsibility of developers to understand, be = familiar with=20 and follow these standards. Any of the standards may be challenged at = any time,=20 but until such challenges have been made and resolved, developers should = conform=20 to the current standards. The process for challenging the standard or = requesting=20 new standards will be documented on the WebSig. The standards contained = in this=20 document are based on, and should shadow any changes to, document=20 MSD_DOCS_116811_2 (Coding Standards for .NET using C#). = The=20 following conventions are used in throughout this document to indicate = that=20 rules should apply in a hard or softer way: = ||Always||<^width=3D"489px"sty= le=3D"BORDER-RIGHT:=20 #ece9d8; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; = PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 366.7pt; PADDING-TOP: = 0in;=20 BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent">This rule must = be=20 enforced||

Never

This action must not happen

Do Not

This action must not happen

Avoid

It is desirable that the action does not happen although some=20 exceptions to this principle may exist

Try

The rule should be attempted where possible

Example

Illustrates a rule

Reason

Explains a rule

Where a rule (or part of a rule) only applies to VB.NET 2005, this = is=20 indicated by a box surrounding the relevant section and the words = "VB.NET=20 2005" in red to the left of the section.=20 ||3.1||||||||<^width=3D"527px"style=3D"BORDER-R= IGHT:=20 #ece9d8; PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: = 5.4pt;=20 PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 395.1pt; = PADDING-TOP: 0in;=20 BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent">Always use = Camel=20 Case or Pascal Case. See section 4 for details where each model is=20 appropriate. ||

3.2

Avoid all upper case names. Single lowercase words are=20 acceptable.

3.3

Do not choose names that begin with numeric characters. =

3.4

Use meaningful, descriptive and specific names.Be consistent = when=20 choosing names e.g. Forename, FirstName.

3.5

Variables and properties should describe the entity not its = attributes=20 such as type or size.

3.6

Do not use Hungarian notation.Example: Dim customerName As = String=20 'GoodDim strCustomerName As String 'Bad!

3.7

Avoid using abbreviations unless the full name is excessively=20 large.Example:Dim bankAccount As Account 'GoodDim bnkct As Account = 'Bad!=20 If abbreviations are used, apply the abbreviated name = consistently.=20

3.8

Do not use reserved words as names.

3.9

Avoid conflicts with existing .NET framework namespaces or data = types.=20

3.10

Try not to add superfluous prefixes or suffixes to = identifiers.Example:=20 Dim customerId As Integer 'GoodDim ipCustomerId As Integer 'Bad! = Public=20 Class Customer 'Good =E2=80=A6End Class Public Class CCustomer = 'Bad! =E2=80=A6End Class=20 Try to avoid naming constructs such as myCustomer, thisCustomer = when=20 dealing with instances of an object. Example:Public Sub = PrintCustomer(BVal=20 myCustomer As Customer) 'Not so good =E2=80=A6End Sub Public Sub=20 PrintCustomer(ByVal customer As Customer) 'Better? =E2=80=A6End = Sub=20

3.11

Avoid including parent class names within a property name where = possible.Example:Dim lastCustomer As StringlastCustomer =3D = Customer.Name=20 'GoodlastCustomer =3D Customer.CustomerName 'Bad! =

3.12

Try to prefix Boolean variables or properties with = =E2=80=9CCan=E2=80=9D, =E2=80=9CHas=E2=80=9D or=20 =E2=80=9CIs=E2=80=9D.

3.13

Append computation qualifiers to variable names like Average,=20 Count.Example:Dim averageSalary As Long 'GoodDim average As Long = 'Bad!=20

3.14

Collection classes should generally be named using the plural = of the=20 constituent type name.Example:Public Class Customer =E2=80=A6End = Class Public=20 Class Customers Inherits CollectionBase =E2=80=A6End Class Where = the singular and=20 plural forms are identical, postfix with the word=20 collection.Example:Public Class TimeSeries =E2=80=A6End Class = Public Class=20 TimeSeriesCollection Inherits CollectionBase =E2=80=A6End Class If = in doubt, adopt=20 a name that will be most clearly understood in the context of the=20 business.Example:Dog and Dogs (if the more common business use is = Dogs)Dog=20 and Pack (if the more common business use is Pack) =

3.15

Always use a prefix when naming GUI controls. This makes it = easier to=20 locate items with intellisense.

Checkbox

chk

Checked List Box

Lst

Combo Box

cbo

Context Menu

ctx

Control (generic)

ctl

Data Grid

grd

Domain up down

dom

Button

btn

Form

frm

Group Box

grp

Help Provider

hlp

Horizontal Scroll Bar

hsb

Image List or Image

img

Label

Lbl

Link Label

lnk

List Box

lst

List View

lvw

MDI child

mdi

Menu Item

mnu

Notify Icon

nfi

Numeric Up Down

num

Open File Dialog

opn

Panel

pnl

Progress Bar

prg

Radio Button

opt

Picture Box

pic

Rich Text Box

rtf

Save File Dialog

sav

Status Bar

sbr

Tab

tab

Text Box

txt

Timer

tmr

Tooltip

tip

Toolbar

Tbr

Track Bar

trk

TreeView

tre

Splitter

spl

Vertical Scroll Bar

Vsb

Naming conventions are applied to various project = entities=20 as shown below ||4.1||<^width=3D"120px"style=3D"BORDER-RIGHT: = #ece9d8;=20 PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; = PADDING-BOTTOM:=20 0in; BORDER-LEFT: #ece9d8; WIDTH: 89.95pt; PADDING-TOP: 0in; = BORDER-BOTTOM:=20 #ece9d8; BACKGROUND-COLOR: transparent">Project File=20 Name||<^width=3D"405px"style=3D"BORDER-RIGHT: #ece9d8; PADDING-RIGHT: = 5.4pt;=20 BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt; PADDING-BOTTOM: 0in; = BORDER-LEFT:=20 #ece9d8; WIDTH: 303.7pt; PADDING-TOP: 0in; BORDER-BOTTOM: #ece9d8;=20 BACKGROUND-COLOR: transparent">Pascal CaseTry to match the Assembly = Name and=20 Root Namespace.Example:Namespace BoE.CCBS.Events.ExampleAssembly=20 BoE.CCBS.Events.Example.dllProject = =E2=80=A6.\BoE\CCBS\Events\Example.vbproj Store the=20 project file in a directory structure that corresponds to the namespace=20 structure. ||

4.2

Source File Name

Pascal CaseAlways match the Class name with the file name.Do = not=20 include multiple classes in a single file.

4.3

Resource File

Pascal CaseUse a descriptive filename.

4.4

Namespace

Pascal CaseTry to partially match the assembly name. =

4.5

Class Name

Pascal CaseUse a noun or noun phrase for the class name.Try to = add an=20 appropriate suffix when sub-classing from another = type.Example:Public=20 Class ForecastItems =E2=80=A6End Class Public Class = PostCodeValidationEventArgs=20 Inherits EventArgs =E2=80=A6End Class

4.6

Structure Name

Pascal CaseUse a noun or noun phrase for the class name.Try to = add an=20 appropriate suffix when sub-classing from another = type.Example:Public=20 Structure ApplicationConfiguration =E2=80=A6End Structure =

4.7

Interfaces

Pascal CaseAlways prefixed with I.Example:Public Interface = IPrintable=20 =E2=80=A6End Interface

4.8

Method

Pascal CaseTry to use a verb or verb-object pair for the=20 name.Example:Public Sub Execute() =E2=80=A6End Sub Public Sub = ExecuteCommand()=20 =E2=80=A6End Sub Public Function GetCustomerAddress() As String = =E2=80=A6End Sub=20

4.9

Property

Pascal CaseUse a name that is representative of the entity = being=20 returned. Do not prefix with Get or Set.Example:Public Property = Name() As=20 String =E2=80=A6End Property

4.10

Field(Public Protected or Friend)

Pascal CaseAvoid if possible. Access via = properties.

4.11

Field (Private)

Camel Case and prefixed with an underscore.Example:Private = _name As=20 String

4.12

Constant

Pascal Case

4.13

Enumeration

Pascal CaseExample:Public Enum CaseStatus Outstanding = InProgress=20 Referred ClosedEnd Enum Additional Note:If bit masking is = required, use=20 the FlagsAttribute. Make the identifying name plural when using = the=20 FlagsAttribute.

4.14

Delegate or Event

Treat as a field with the relevant access = modifier.Example:Public Event=20 LoadPlugin As EventHandler

4.15

Local Variable

Camel CaseAvoid using single character variables except in for=20 loops.Avoid enumerating variable names like text1, text2, text3.=20

4.16

Parameter

Camel CaseExample:Public Sub Execute(ByVal commandText As = String,=20 _ByVal interationCount As Integer) =E2=80=A6End Sub =

4.17

Namespace Construction

Follow a standard pattern for namespace = constructionBoE.[Business Area/=20 Project/Functional Area].[Application Name/Shared].[Logical=20 Layer/Technology].[Sub Grouping]=20 = Example:BoE.CCIT.FoI.BusinessEntitiesBoE.Markets.FiguresChief.WebUI=20

||5.1||<^width=3D"527px"style=3D"BORDER-RIGHT: = #ece9d8;=20 PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt;=20 PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 395.1pt; = PADDING-TOP: 0in;=20 BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent">Always = declare only=20 one namespace per file (see 4.1).Use the namespace convention = described in=20 4.17. ||

5.2

Avoid including multiple top level classes in one file (see = 4.1).=20 Nested class declarations are permissible.

5.3

Use a tab indentation size of 4. This may be set up in Visual = Studio.=20

5.4

Declare variables independently using a separate line for each. =

5.5

Place namespace =E2=80=9CImports=E2=80=9D statements at the top = of the file.Try to=20 group =E2=80=9CImports=E2=80=9D statements so that System = namespaces appear above custom=20 namespaces.Example:Imports System.WebImports System.TextImports=20 BoE.CCBS.Events

5.6

Group internal class implementation as follows:Member = VariablesNested=20 Enumerations, Structures and ClassesConstructors and=20 DestructorsPropertiesMethods

5.7

Try to order declarations within the groups above (5.8) based = upon=20 their access modifier:PublicProtectedFriendPrivate Only use other = layouts=20 where clarity would be improved as a result.

5.8

Segregate Interface implementation using #Region statements. = Use=20 comments on #End Region statements if this improves=20 clarity.Example:#Region "Public Interface" =E2=80=A6#End Region = 'Public Interface=20

5.9

Append the folder name to the namespace for source files = residing in=20 sub folders.

5.10

Indent all code blocks contained within braces. =

5.11

Use CRLF and tabs to separate and organise code. =

5.12

Avoid declaring multiple attributes on the same line.=20 Example:<Attribute1, _Attribute2> _Public Class Customer = =E2=80=A6End Class=20

5.13

Avoid superfluous formatting such as additional spaces to line = up=20 variable declarations.Example:Dim someVariable As Integer =3D 1 = Dim=20 anotherVariable As StringBuilder =3D New StringBuilder()Dim=20 yetAnotherVariable As SomeVeryLongClassName =3D New=20 SomeVeryLongClassName()

||6.1||<^width=3D"527px"style=3D"BORDER-RIGHT: = #ece9d8;=20 PADDING-RIGHT: 5.4pt; BORDER-TOP: #ece9d8; PADDING-LEFT: 5.4pt;=20 PADDING-BOTTOM: 0in; BORDER-LEFT: #ece9d8; WIDTH: 395.1pt; = PADDING-TOP: 0in;=20 BORDER-BOTTOM: #ece9d8; BACKGROUND-COLOR: transparent">Allow VSS to = track=20 changes to source files, when checking in source files use the VSS = comments=20 field to add a summary description of the changes and include any = references=20 to external documents or T-plan logs. Add detail comments in the code = as=20 described in the other points of this section. ||

6.2

Use ' or .

6.3

Add comments only where they describe functionality or process = that is=20 not obvious from looking at the code, or not covered in other=20 documentation such as sequence diagrams.

6.4

Avoid flowerboxing comments (adding superfluous formatting=20 characters).Example:'

' Begin Save Process'

6.5

Try to use the comment keywords where appropriate to make your = comments=20 appear in the Visual Studio Task List. (See MSDN=20 for more information about task list keywords).Example:'UNDONE: = Save=20 disabled, waiting for DB changes to be completed.'HACK: Temporary = fix=20 until the Config reader is implemented.'TODO: Exception logging = needed=20 here.

6.6

Always use VBCommenter comment blocks () for public, = protected=20 and friend declarations.Avoid using comment blocks for private=20 declarations unless required for documentation generation for = example.=20

6.7

Always include <summary> comments.Include <param>,=20 <return> and <exception> where appropriate. =

6.8

Always add CDATA tags to comments which have embedded code or = markup to=20 avoid encoding issues.Example:<example>Add = the=20 following section to=20 = =E2=80=9CappSettings=E2=80=9D<code><![CDATA[=20 <configuration> <appSettings> <add = key=3D=E2=80=9DExampleSetting=E2=80=9D = value=3D=E2=80=9DExampleValue=E2=80=9D>=20 </appSettings>=20 = </configuration>]]></code></example>= ;

||||||

7.1.1

Do not omit access modifiers. Explicitly declare all = identifiers with=20 the appropriate access modifier instead of allowing the default.=20

7.1.2

Avoid mutual references between assemblies.

7.1.3

Do not use the default assembly versioning scheme for COM = Visible=20 assemblies as this may cause GUIDs to change and break client=20 interoperability. Increment AssemblyVersionAttribute manually in = this=20 case.

7.1.4

Set ComVisibleAttribute to False for all assemblies. = Selectively enable=20 the ComVisibleAttribute for individual classes. =

7.2.1

Try to initialise variables where you declare them.Example:Dim = counter=20 As Integer =3D 0

7.2.2

Use the simplest data type required e.g. use an Integer over = Long=20 unless there is a requirement to store 64 bit numbers. =

7.2.3

Try to use the CTS types in preference to the language type = aliases to=20 achieve standardisation between VB.Net and C#.Example:Dim = countThis As=20 System.Int32 'GoodDim countThat As Integer 'Bad! =

7.2.4

Avoid using inline numeric literals (magic numbers) use = constant or an=20 enumeration instead.

7.2.5

Avoid using inline string literals. Use constants, resources, = registry=20 or configuration file entries instead.

7.2.6

Only use constants for simple types.

7.2.7

Avoid boxing and unboxing value types.Example:Dim count As = Integer =3D=20 1Dim refCount As Object =3D count 'Implicit boxing = operation=E2=80=A6 'Do some=20 processingDim newCount As Integer =3D DirectCast(refCount, = Integer)=20 'Explicit unbox operation

7.2.8

Prefer String.Format or StringBuilder over concatenation.=20

7.2.9

Do not compare strings to String.Empty. Compare by using = String.Length=3D=20 0.

7.2.10

Avoid hidden string allocations in loops. Use String.Compare()=20 instead.Reason:Some string operations ToLower() involve temporary = string=20 allocations

7.3.1

Avoid recursive methods where loops or nested loops would = serve.=20

7.3.2

Avoid using For Each to iterate immutable value type = collections.=20

7.3.3

Do not modify enumerated items within a For Each loop. =

7.3.4

Avoid evaluating Boolean conditions against True or=20 False.Example:'Avoid this SyntaxIf IsValid =3D TrueThen = =E2=80=A6End If 'Use This=20 SyntaxIf IsValid Then =E2=80=A6End If

7.3.5

Avoid complex compound Boolean evaluations.Example:'Avoid This = SyntaxIf=20 (value>MedianValue) AndAlso Not (value=3DMeanValue) AndAlso=20 (stateChanged) Then =E2=80=A6End If 'Preferred SyntaxDim isMedian = As Boolean=20 =3D(value > MedianValue)Dim isMean As Boolean =3D Not (value = =3D=20 MeanValue)Dim isStateChanged As Boolean =3D(stateChanged) If = (isMedian=20 AndAlso Not isMean) AndAlso isStateChanged Then =E2=80=A6End If =

7.3.6

Use case statements (Select Case) for simple operations with = parallel=20 conditional processing or for operations with more than 3 = possibilities.=20 Include an Else case when using a case statement. =

7.3.7

Prefer polymorphism over case statements to encapsulate complex = operations.

7.4.1

Do not use try catch blocks for controlling the flow of program = execution. Slightly Contrived Example:' Always attempts an insert = and if a=20 violation occurs on the primary key' try an updateTry=20 InsertCustomer(=E2=80=A6.)Catch ex As PrimaryKeyViolationException = UpdateCustomer(=E2=80=A6.)End Try ' More explicit decision point = and flow=20 controlTry If customer.IsNew Then InsertCustomer(=E2=80=A6) Else = UpdateCustomer(=E2=80=A6)=20 End IfCatch ex As SqlException =E2=80=A6End Try =

7.4.2

Only catch exceptions that you are going to handle. =

7.4.3

Use exception filters where possible.

7.4.4

Avoid re-throwing an exception. Allow it to bubble up the call = stack=20 instead.

7.4.5

If re-throwing an exception omit the exception argument from = the throw=20 statement so the original call stack is preserved.Example:'Correct = =E2=80=93=20 Preserves the call stackTry =E2=80=A6Catch ex As SqlException = ThrowEnd Try=20 'Incorrect =E2=80=93 Call stack is lostTry =E2=80=A6Catch ex As = SqlException Throw exEnd=20 Try

7.4.6

When throwing a new exception always pass the inner exception = in order=20 to maintain the exception tree and inner call stack. Additional = Notes=C2=B7=20 Where throwing an exception across a trust boundary (e.g. from a=20 middle-tier to client) you may not want to pass the inner = exception to=20 avoid potentially sensitive information about the application = being=20 exposed. In such a case, the original exception should be logged = somewhere=20 first, to aid diagnostics.=C2=B7 Serializing exception trees = across boundaries=20 may be slow, so be pragmatic.

7.4.7

Use validation to avoid exceptions. Program defensively.=20

7.4.8

Avoid custom exception classes in favour of existing exception = classes.=20

7.4.9 VB.NET2005

Where custom exceptions are necessary:Derive from=20 ExceptionnotApplicationException.Override ToString() to provide=20 serialization. Override String Widening operator to provide = serialization.=20 Implement the following constructor overloads:Public Sub New() = =E2=80=A6End Sub=20 Public Sub New(ByVal message As String) =E2=80=A6End Sub Public = Sub New(ByVal=20 message As String, ByVal innerException As Exception) =E2=80=A6End = Sub=20

7.4.10

Always add an Application.ThreadException handler in windows = forms=20 applications to catch any unhandled exceptions and close-down = gracefully=20 after displaying a suitable message to the user. Otherwise, the = default=20 exception message is displayed and the application will terminate=20 immediately.

7.4.11

Avoid swallowing exceptions. If this behaviour is desired, = ensure=20 comments are added to justify the choices made.

7.5.1

Always declare types explicitly with a namespace to ensure = global=20 uniqueness. e

7.5.2

Avoid declaring methods with more than 7 parameters. Consider=20 refactoring or using an object or structure to pass information = instead.=20

7.5.3

Avoid using the Shadows keyword to hide members of a derived = type.=20

7.5.4

Only use the MyBase keyword to invoke the base class = constructor or=20 base implementation within an override.

7.5.5

Do not use the protected access modifier in classes declared as = NotInheritable.

7.5.6

Validate enumerated type variables before consumption when = converting=20 from an Integer or name representation.Example:Dim statusCode As = Integer =3D=20 21If Enum.IsDefined(GetType(CaseStatus), statusCode) Then = =E2=80=A6End If=20

7.5.7

Avoid overriding Equals and the Equality operator without good = reason.=20 See 7.5.8 for some base guidelines.

7.5.8 VB.NET 2005

Guidelines for Implementing Equals and the Equality Operator = (=3D): =C2=B7=20 Consider overriding Equals() on a Structure or other value = type.=C2=B7=20 Implement the GetHashCodemethod whenever you implement the Equals = method.=20 This keeps Equals and GetHashCode synchronized. =C2=B7 Override = the Equals=20 method any time you implement the IComparable=20 Interface. =C2=B7 Do not throw exceptions from the Equals or = GetHashCode=20 methods. =C2=B7 Consider overriding the equality operator (=3D) on = a Structure or=20 other value type.=C2=B7 Override the Equals method whenever you = implement =3D,=20 and make them do the same thing. This allows infrastructure code = such as=20 Hashtable=20 and ArrayList,=20 which use the Equals method, to behave the same way as user code = written=20 using =3D. =C2=B7 You should consider implementing operator = overloading for the=20 equality (=3D), not equal (<>), less than (<), and = greater than=20 (>) operators when you implement IComparable.=C2=B7 Do not = throw exceptions=20 from the equality operator (=3D). Further=20 = Information:[http://msdn.microsoft.com/library/default.asp?url=3D/library= /en-us/cpgenref/html/cpconimplementingequalsoperator.asp=20 Guidelines for Implementing Equals and the Equality Operator = (=3D=3D)]=20

VB.NET 2005

Consider overriding the Widening operator when overriding=20 ToString().Further=20 = Information:[http://msdn.microsoft.com/library/en-us/dnvs05/html/vboperat= oroverloading.asp?frame=3Dtrue#vboperatoroverloading_topic4=20 Operator Overloading in Visual Basic 2005]

7.5.19

Avoid Parameter Arrays. Use overloading instead or use a = structure or=20 object to encapsulate the parameters you wish to pass. = Reasons:=C2=B7 There=E2=80=99s=20 no enforceable limit to the number of arguments received in this = way=C2=B7 If=20 multiple types need to be supported the parameter array must be = typed as=20 object=C2=B7 Can only have one parameter array (params) per method = signature=C2=B7=20 Can=E2=80=99t specify out parameters=C2=B7 Object encapsulation is = more extensible=20

7.5.10

Avoid public nested classes, structures and enums. They should = only be=20 used internally and therefore declared protected or private. Some = useful=20 guidance on when to use nested classes:Recommendations=20 on Nested Classes in Components

7.5.11

Always implement IDisposable in classes that use external = resources:=20 Public Sub Dispose() Dispose(True) GC.SuppressFinalize(Me)End Sub=20 Protected Overloads Overridable Sub Dispose(disposing As Boolean) = If=20 disposing Then 'Free managed objects End If 'Free unmanaged = objectsEnd Sub=20

7.5.12 VB.NET 2005

Wrap instantiation of IDisposable() objects with a using = statement to=20 ensure Dispose() is called automatically.Example:Using = dbConnection As New=20 SQLConnection(_connectionString) =E2=80=A6End Using =

7.5.13

Always call Close() and/or Dispose() on objects that offer=20 it.

7.6 Events and Delegates

7.6.1

Always check delegate instances for Nothing before invocation.=20

7.6.2

Use EventHandler and EventArgs for simple events. =

7.6.3

Derive a custom EventArgs class to provide additional data.=20

7.6.4

Use CancelEventArgs to give control to the subscriber. =

Threading is a large and complex topic and = solutions=20 should be carefully designed and programmed to avoid deadlocks and = race=20 conditions. It is possible to get threading badly wrong leading to = subtle=20 bugs that are very difficult to track down.

7.7.1

Prefer the Monitor type rather than SyncLock for fine grained=20 control.Reason:Supports defensive coding with TryEnter(). =

7.7.2

Do not lock value types.Example:Dim isDisposing As = BooleanSyncLock=20 isDisposing 'BAD =E2=80=93 Do Not lock value types (implicit = boxing) =E2=80=A6End SyncLock=20 Further = Information:[http://www.haacked.com/archive/2005/04/12/2634.aspx=20 Threading Tips: Never Lock a Value Type. Never Lock "This"]=20

7.7.3

Do not lock the current instance despite the amount of = documentation=20 from Microsoft demonstrating this solution. Example:SyncLock Me = 'BAD =E2=80=A6End=20 SyncLock Do not lock on a type.Example:SyncLock GetType(Customer) = 'BAD=20 =E2=80=A6End SyncLock Lock on a private variable = instead.Example:SyncLock=20 GetType(somePrivateStaticObject) 'Good code! =E2=80=A6End SyncLock = Reasons:A full=20 discussion of the issues with these techniques is discussed = below.A=20 Special Dr. GUI: Don't Lock Type Objects!

7.7.4

If all you need to do is increment, decrement an Int32 or Int64 = value,=20 or set a 32-bit value (an Int32, Object or Single), use the = Interlocked=20 class. Reason:This won't block your thread. It's operations are=20 special-cased by the CLR to be performed by an single CPU = instruction, so=20 they can't be pre-empted by another thread half-way through.=20

7.7.5

Synchronising Data for Multithreading.A number of other = synchronisation=20 mechanisms are discussed in these articles:Safe = Thread=20 Synchronization Synch= ronizing=20 Data for Multithreading

last edited 2005-12-05 = 10:08:41 by=20 OwenJones

Navigation

Page

User

Recently viewed pages