Saturday, December 29, 2007

Still Learning

Even though I created Suneido and have used it pretty heavily for years, I still find myself learning better ways to apply it. (I think that's part of the reason I like programming.)

Suneido uses the open source Scintilla editor. ScintillaControl is the "wrapper" that interfaces Scintilla to Suneido's user interface framework. I needed to add a new method to it today:


I noticed I had a lot of these methods and I started wondering whether there wasn't a better alternative to adding so many simple repetitious methods. Ruby, and especially Rails, which I've been involved with on another project, make heavy use of "catching" calls to missing methods and implementing them.

I was able to replace all these simple methods with:

f = method.Upper()
if not SCI.Member?(f)
throw "method not found: " $ method
return .SendMessage(SCI[f])

"Default" is Suneido's way to "catch" calls to missing methods.

Then I realized I could generalize it to handle methods with arguments:

f = args[0].Upper()
if not SCI.Member?(f)
throw "method not found: " $ args[0]
args[0] = SCI[f]
return .SendMessage(@args)

"@args" is used to capture all the arguments and then pass them again. args[0] will be the method name.

This allowed me to remove a bunch of methods and I won't have to add any more in the future.

In addition, I noticed I had a lot of calls like .SendMessage(SCI.GETLINECOUNT) within the wrapper code. These could now be simplified to be like: .GetLineCount()

This would all fall into the category of "refactoring" since I'm improving the code without changing its behavior. (Strictly speaking, the behavior has changed slightly, but not in a way that should affect existing code unless someone is doing something unusual.)

I guess you'd call this refactoring something like: "Replace explicit methods with catching missing method calls."

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