COM error handling best practice Error hanlding C#

COM:

COM stands for Component Object Model is a binary-interface standard for software components introduced by Microsoft in 1993. It is used to enable inter-process communication object creation in a large range of programming languages.

Most of the COM functions and interface methods return a value of the type HRESULT which is really frustrating for a developer. HRESULTs are really not handles to anything; they are only values with several fields encoded in the value. As per the COM specification, a result of zero indicates success and a nonzero result indicates failure.

At the source code level, all error values consist of three parts, separated by underscores. The first part is the prefix that identifies the facility associated with the error, the second part is E for error, and the third part is a string that describes the actual condition. For example, STG_E_MEDIUMFULL is returned when there is no space left on a hard disk. The STG prefix indicates the storage facility, the E indicates that the status code represents an error, and the MEDIUMFULL provides specific information about the error. Many of the values that you might want to return from an interface method or function are defined in Winerror.h.

How to return error information?

Using the COM error-handling interfaces and functions, you can return error information by performing the following the steps:

Implement the ISupportErrorInfo interface.
To create an instance of the generic error object, call the CreateErrorInfo function.
To set its contents, use the ICreateErrorInfo methods.
To associate the error object with the current logical thread, call the SetErrorInfo function.

ISupportErrorInfo

public void InterfaceSupportsErrorInfo (ref Guid& riid);

CreateErrorInfo

HRESULT CreateErrorInfo(
  ICreateErrorInfo **pperrinfo
);

pperrinfo [Out] . Address where error information creation object will be stored.

Result

Success: S_OK.
Failure: HRESULT code.

SetErrorInfo

HRESULT SetErrorInfo(
  ULONG      dwReserved,
  IErrorInfo *perrinfo
);

dwReserved [in] Reserved for future use; must set to zero.
perrinfo [in] Pointer to an error object that supports IErrorInfo.

Success: S_OK.
Failure: HRESULT code.

Share on Facebook

Export Generic Collection to PDF ASP.Net Core MVC

PDF Sometime you may in need to export data in PDF. Following code will use Syncfusion Package and give you ready made Table pushed from Generic collection. Put below code in Repository Put below code in Controller JavaScript Code Finally you can attach id to an element in html and in JavaScript on Document ready […]

Export Excel ASP.Net Core MVC

Excel Export Following Example helps you to export excel from database in a generic way using EPPlus library. Requirement EPPlus Nuget Package Code to Repository Supporting Method Code to Controller Code to JavaScript JavaScript Supporting Method You can hit ExportToExcel() call in document ready method in JavaScript document by pointing any id written in HTML […]

Save/Retrieve Session ASP.Net Core MVC

Session Plays a vital role while dealing with caching in your browser. ASP.Net Core offers Session caching fast and reliable way. Here is the practical example. Put following code anywhere in common class or Repository, it has two methods Generic in nature Add/Get. Add Method will allow you to cache object in Browser memory and […]

Number List in Word Document using C# code example

Number List Microsoft Word offers feature by which you can auto number your list in various formats. In this article we will write code to dynamically generate a numbered list in a document using C#. C# Code example Note: You have to add Microsoft Word Interop library as reference to enable Using statement or create […]

Sorting in Microsoft Word using VBA (Visual Basic for Applications)

Sorting Do you know, Microsoft Word has capability to perform sorting over a document. In this article we will write code to sort paragraphs in Alphabetical order using visual basic for applications code. Before code Code example Put above code in a module, Select number of paragraphs that you would like to sort in A-Z […]

EPPlus Open Office Xml Office solution using C#

EPPlus Is an open Office XML solution, highly useful library capable to manipulate Microsoft Excel similar to Introp APIs. Why EPPlus? As per Microsoft the solutions (Excel, Word, PowerPoint, Outlook etc) built for client architecture but what about Servers? Let’s take an example that I have recently faced and EPPlus helped me a lot here. […]

String vs StringBuilder C#.Net with code example

String C# class which offers capability to store any type of string data into a variable. Strings are immutable (non-modifiable) cause performance overhead because each time we modify a string it creates a copy of modified instance into the memory, hence, as a practice string should be avoided for large string operations. Following is the […]

Var vs. Dynamic C# with code example

Var vs. Dynamic C# offers variety with flavors to accomplish the task to the developers. var keyword defines a static nature which gets resolve at compile-time introduced in C# 3.0 where dynamic gets resolved at runtime introduced in C# 4.0. Var is a statically type variable, which means values of these variables gets decoded at […]

Multi-threading in C#.Net with step by step code example

Multi-threading Is a concept to execute multiple tasks or process simultaneously. Basically multi-threading enables paths to your application to execute multiple processes. Multi-threading can be achieved in C# using System.Threading name space which provides complete control over threading. Let’s write example code where we will execute two different methods to print numbers using loop and […]

Create a progress bar in Excel using VBA (Visual Basic for Applications)

Progress bar In this article we will create one progress bar using Excel vba with step by step example. User can change feel and look of the UserForm as per their need and mimic the logic to fit in their solution. Design Insert a user form Add one label on it and change Caption property […]

COM error handling best practice

Leave a Reply Cancel reply

Export Generic Collection to PDF ASP.Net Core MVC

Number List in Word Document using C# code example

EPPlus Open Office Xml Office solution using C#

String vs StringBuilder C#.Net with code example

Var vs. Dynamic C# with code example

RSS feed

Subscribe to our articles