Proce ss: Incremental Development of DSLs in Visual C#

Drawing QR Code ISO/IEC18004 in Visual C# Proce ss: Incremental Development of DSLs
Proce ss: Incremental Development of DSLs
QR Encoder In C#.NET
Using Barcode generator for Visual Studio .NET Control to generate, create QR Code 2d barcode image in .NET framework applications.
issues that are in a given state An administrator can de ne a set of allowed states, and users can set the state of any issue to one of those values This allows different states to be employed from one client to another But one of CJKW s earliest customers has a more stringent requirement, that there should be some constraints on how states can be changed for example, that you can t go straight from Unassigned to Fixed
Bar Code Creator In C#.NET
Using Barcode printer for .NET framework Control to generate, create barcode image in .NET applications.
Figure 2-1: The web interface to the Issue Tracker application
QR Creation In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
Looking at the existing code, CJKW s in-house developers identify the point at which the menu of allowed states is presented to the user They insert some code that computes the set of permitted next states from the previous one (After an initial test, they realize that they must always include the current state in the allowed list so that the user has the option of leaving the state unchanged) The relevant fragment looks like this:
Quick Response Code Generation In Visual Studio .NET
Using Barcode creation for .NET framework Control to generate, create QR-Code image in VS .NET applications.
2: Creating and Using DSLs
Print QR In Visual Basic .NET
Using Barcode generation for .NET framework Control to generate, create QR Code image in Visual Studio .NET applications.
string[] nextOptions = new string[]{}; if (!stringIsNullOrEmpty(currentState)) { if ("Unassigned"==currentState)2 nextOptions = new string[] { "Unassigned" // allow leaving state unchanged "Approved", "Rejected", }; else if ("Rejected"==currentState) nextOptions = new string[] { "Rejected", // allow leaving state unchanged }; else if ("Approved"==currentState) nextOptions = new string[] { "Approved", // allow leaving state unchanged "Fixed", }; else if ("Fixed"==currentState) nextOptions = new string[] { "Fixed", // allow leaving state unchanged }; } else { // New Issue nextOptions = new string[] {"Unassigned"}; }
Bar Code Drawer In C#
Using Barcode generator for .NET Control to generate, create bar code image in .NET framework applications.
The rst instance of this application works well at the customer site, and CJKW decided to use it with its other clients though of course with more or less differing requirements in each one The development team s initial response is to copy the existing code and modify it to meet the new requirements at each customer site But as CJKW thrives and more customer engagements arise, it becomes clear that this is an unscalable strategy that creates too many variants of the same code To be fair to CJKW, it wasn t clear at the outset that there would need to be so many variations on the same application, and it wasn t clear which bits would be the same all the time and which bits would vary So for a while the developers create a new variant for each customer, adapt the code for each new requirement, and often take the opportunity to make some architectural improvements at the same time But eventually, Devika, the lead
Bar Code Creation In Visual C#.NET
Using Barcode maker for .NET framework Control to generate, create barcode image in .NET framework applications.
2 The CJKW developers show some naivet with respect to coding practice The repetitive use of literal strings is inadvisable And, as they discovered eventually, bolting the statechart into the UI code isn t the best strategy However, the fragment serves to illustrate the example
Encode Code39 In C#.NET
Using Barcode printer for Visual Studio .NET Control to generate, create Code 39 Full ASCII image in Visual Studio .NET applications.
Proce ss: Incremental Development of DSLs
Code128 Generation In Visual C#.NET
Using Barcode creation for .NET Control to generate, create USS Code 128 image in .NET applications.
developer, sits back and surveys with some concern the source repository, full of half-forgotten variations of the same system She does a series of text comparisons on the source of the applications that have been developed to date a variability analysis It turns out that the above fragment of state transition code is one of the main things that changes from one installation to another The team therefore decides that this part of the code should be generated from a model There are other miscellaneous bits of code that change from customer to customer, but this particular aspect is consistently variable, so automating its development would save a lot of time both in creating the code initially for each new application and in making any changes later In this way, the need for generation in a particular area is identi ed bottom-up, by considering necessary variations in the implementation Some other variations were found in the diff, but they turn out to be incidental, without signi cant effect on function To realize its plan, the team must produce two things: A DSL de nition A body of code, derived from their current code base, the variable parts of which can be generated from the DSL What kind of DSL is suitable for this purpose Well, in this case, states seem to suggest state diagrams, so let s hope the team didn t spend too long pondering that one Figure 2-2 shows an example of the DSL they produce
DataMatrix Creator In C#
Using Barcode creation for .NET Control to generate, create Data Matrix 2d barcode image in .NET applications.
Creating Bar Code In Visual Studio .NET
Using Barcode creation for VS .NET Control to generate, create bar code image in VS .NET applications.
Generate Barcode In Visual Studio .NET
Using Barcode creator for VS .NET Control to generate, create bar code image in .NET applications.
Paint Bar Code In Java
Using Barcode generator for Java Control to generate, create barcode image in Java applications.
Data Matrix ECC200 Generation In Visual Basic .NET
Using Barcode generation for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in .NET framework applications.
Code 39 Extended Printer In Java
Using Barcode creation for Java Control to generate, create ANSI/AIM Code 39 image in Java applications.