File-Logging in Delphi

I wanted to do some quick logging to help me understand some code flow in Delphi. But having the Starter Edition of Delphi was crimping my style! Starter Edition doesn’t include the Event Log Viewer to see the output from OutputDebugString() while running in the debugger.

So I kept coming back to “I really just need to get over the learning curve and set up a ‘proper’ logging tool like Log4J”, a tool I’d used for Java projects in times long past. StackOverflow suggested Log4D and Log4Delphi as good possible candidates.

After reviewing both packages, I decided to go with Log4D.

Log4D seemed a bit simpler in that everything you need for basic logging is in one .pas file and one .inc file. I can see advantages both ways as a developer, but for just get me some logging quick, only having to add two files rather than a handful, and only needing one new unit in the uses statement simplifies some things.

Neither one had been updated in the last few years, so when you’re talking about “make this compile in a current version of Delphi” it looked like similar level of work.

Log4Delphi claims to be “loosely based on” Log4J. Log4D claims to be a direct port of Log4J.

Log4Delphi appears to be fairly well documented, whereas Log4D has almost no documentation. And while usually I prefer to go with the well-documented version, I felt like the simplicity of one file would make it worth seeing if I could muddle through the lacking documentation to make Log4D work. A few Delphi experts on StackOverflow swear by Log4D.

There were two compile errors I had to fix to make Log4D compile on XE4:

The IFDEF around Contnrs is missed by newer versions of Delphi, so you need to add {$DEFINE DELPHI5_UP} to the end of the .inc file (or in the .pas file works too). And ShortDateFormat needed to change to FormatSettings.ShortDateFormat

That’s the bare minimum fix, a better fix that maintains backwards compatibility isn’t a whole lot harder See my StackOverflow Discussion here about fixing the IFDEF so “and above”. And the ShortDateFormat issue, just needs another IFDEF around the FormatSettings for XE+.

The only basic “how to get this up and running” example of Log4D I could find online was this one blog entry. It needed a couple changes to compile (“Trace” wasn’t one of the log levels in the downloaded Log4D package). And then a little more puzzling together from the code and documentation for Log4Delphi and Log4J to make a file logger. I’ll write more about those changes in my next post ;-).

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