Compiled dmd2.032 in VC++ 2009!

[bearophile]

Jeremie Pelletier:
> I also made a simple D script to rename all c files to cpp:

Generally I suggest to use a scripting language to do a similar task (or a simper linux shell script, probably one or two lines), but I agree that doing this I can't see possible faults/troubles of the same D code. So in the end writing it in D is a good experiment.

You are probably an expert programmer, yet in your script I see some things that in my opinion are better done in other ways:
- Don't init things to void unless your performance experiment tells you to, and do it with care. This is explained in D documentation too. The speed gain is very limited and the risk of giving false pointers to the conservative GC is present, because currently it's not very precise.
- Gotos aren't evil, but it's better to use them only as performance optimization or for tricky flows of the code. Generally in D there are better ways to solve such problems. For example you can just throw an exception if args.length!=2, and the uncaught exception will show an error message to the user and the code will stop.
- try ... catch(FileException) {} looks not nice.
- if(de.name[$-2 .. $] == ".c") is a bit unsafe, because unlike Python D slices aren't saturating (and in the meantime I have asked to the Python developers, they have told me that this design is desired in Python, it's not a design mistake left for backward compatibility as someone here told me. And it's a very handy thing. The only advantage of the way D slices are done is that D ones are a bit faster. But their unsafety unnerves me and forces me to write uglier and longer code). Generally it's better to use string functions, that are safer. Python has endswith() and startwith() string methods that in D (as functions) are even more important.
- In D the main doesn't need to return an int in an explicit way. If your program stops because you have thrown and exception, I think the return value is not zero.
- Generally don't use this: printf("Usage: %.*s <path>", args[0]); printf() is good mostly to speed up output if you have to print tons of things, or in debugging write* functions, or for a simple compatibility with Tango. Generally use writeln or writefln.
- Unless performance is critical, it's generally better to write script-like D programs in a high-level style, because in such kind of programs the purpose is to write the code quickly, to have readable code, and most of all to have the most reliable code as possible. In such small programs saving microseconds is usually not positive.
- Note for D developers, listdir() desiged like that isn't good. Python too used to have something similar (os.path.walk()), but it's better to invent its design, and give an interable that instead yields the nodes of the tree (os.walk() from Python 2.3).

Bye,
bearophile