Re: [fpc-pascal] for .. in loop implementation
Vinzent Höfler schrieb: Jürgen Hestermann wrote: Mantra: First make it work, then make it fast. In general that's true from the programmer's viewpoint. But this does not apply to adding language details because there is no 'first make it work'. Why obscure important implementation details if the only benefit is saving some writing? I won't judge on the only save some writing here, but generally it *does* apply to language features: If a particular language feature helps you writing correct code faster (by supporting you to make it work instead of relying on your abilities to use the debugger), then it does apply. The real question is if the (or any other) proposal is good enough to do just that, or if it's really some syntactic sweetener (not even sugar, sugar at least contains energy). That's something to discuss. There is not much to discuss: Who has time to implement it without hurting the implementation of other maybe more important stuff. If someone provides usable (readable, commented code with tests, full implementation support also the iterating interfaces) patches to implement the for in ... stuff I'am sure they get applied. Let me take a rather extreme point of view: After all, all those for-, while-, and repeat-until-loops are only there to save you from some typing work[0], because Pascal already has a perfectly good loop-construct with which you can do all that: goto. Would you agree here? Probably not. Not really because the use case of typical while/for/repeat loops is much wider. How often do you iterate over the odd days of a week? ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementation
Marco van de Voort wrote: In our previous episode, leledumbo said: The latter one has iteration overheads, while the former can be optimized to loop as many as needed. I'm not saying I'm the best Pascal programmer, but in case there's a (better) solution to this (rather than extending the language) please tell me. Your assesment is correct as far as I can see. However IMHO that doesn't meant you are right. One single case of an optimalization advantage, and then in a border case like iteration over a constant set does not justify a language extension. What is the negative of adding it? To me, I program in a language because it makes my life easy, not because each keyword has a certain/clear purpose and cannot be done any other method. The easier FP is for me to program in (or the less typing I have to do), the better FP is to me. I'm confused on why not to add it. Jeremy ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementation
In our previous episode, Jeremy Cowgar said: However IMHO that doesn't meant you are right. One single case of an optimalization advantage, and then in a border case like iteration over a constant set does not justify a language extension. What is the negative of adding it? Clutter, maintenance, and somebody has to do both implementation and maintenance, addition to documentation tool, pretty printer etc. To me, I program in a language because it makes my life easy, not because each keyword has a certain/clear purpose and cannot be done any other method. The easier FP is for me to program in (or the less typing I have to do), the better FP is to me. I'm confused on why not to add it. Easy and typing are not related. Easy allows me to do my job quickly. Typing has never been limiting in my job. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementationt
In our previous episode, Jeremy Cowgar said: Clutter, maintenance, and somebody has to do both implementation and maintenance, addition to documentation tool, pretty printer etc. I wonder how much maintenance would actually have to be done? Once a language construct is present, does it really take that much to keep it up? Well, I only see the practice from years of reading bugreports, but : often bugreports pertaining to language features are about special cases and interactions between features. Like automated types, properties etc. What if the right side is an expression instead of a value or a constant? What if it involves ref counted types, what if it involves a temp location ? Etc. The same for the additions to documentation, pretty printer, etc... It's all done once and should be fine after that. After a few additions, patches and tweaks, usually yes. And then it turns up that Delphi also accepts after in etc. However, I am speaking out of a not ever looking at the compiler source, so I may be pretty far off base. Just thinking aloud. People typically only think of a few standard cases like there are in the manual. It is a totally different magnitude to fix any constuction the users find in their existing Delphi code. If you think it is worth it, by all means go ahead. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementation
Vinzent Höfler schrieb: I won't judge on the only save some writing here, but generally it *does* apply to language features: If a particular language feature helps you writing correct code faster (by supporting you to make it work instead of relying on your abilities to use the debugger), then it does apply. What I fear (from observing the last decade or two) is that the language becomes bloated by adding one gimmick after the other just to say me too. Every new feature is something that a (new) user has to learn about. And the more types of FOR loops you add the more confusing it gets. Let me take a rather extreme point of view: After all, all those for-, while-, and repeat-until-loops are only there to save you from some typing work[0], because Pascal already has a perfectly good loop-construct with which you can do all that: goto. Would you agree here? Probably not. Of course not. But would you on the other side agree with adding each and every gimmick mankind can think of? Probably not either. Maybe, but you started talking about performance. ;-) Nono, you did: Everything that obscures what's going on under the hood has the potential to generate performance problems. You are right that not you started talking about performance but leledumbo in his starting post about this topic where he assumed a performance gain: The latter one has iteration overheads, while the former can be optimized to loop as many as needed. So none of us started talking about it. ;-) So to get to the point, finally: The argument that some particular language construct has the potential to generate performance problems is NIL. IMNSHO. I doubt that. I often stumble over programs which are awfully slow (Novell Salvage Dialog for examples sometines needs many minutes to sort 80 objects!). And that compared with the everywhere heard statement You don't need to think about performance, it's only important that it runs at all makes me thinking. Many programmers simply don't know about how their mighty language functions perform and what they do in the background. But without knowing this you don't even have an idea of how fast it will be. I also had such experience with Virtual Pascal where the FindFirst/FindNext API functions are obscured by an extra layer to support multiple platforms (which I didn't know at first). I only wondered why my simple scan program for the creation date of files took 2 days on our server. After removing all the overhead by directly using FindFirst/FindNext from the windows API it boosted up to 6 hours only. Sure, many people don't care whether a program runs 2 days or 6 hours but I do. Jürgen Hestermann. ___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] for .. in loop implementation
On 08 Jan 2009, at 19:01, Jürgen Hestermann wrote: I doubt that. I often stumble over programs which are awfully slow (Novell Salvage Dialog for examples sometines needs many minutes to sort 80 objects!). And that compared with the everywhere heard statement You don't need to think about performance, it's only important that it runs at all makes me thinking. Many programmers simply don't know about how their mighty language functions perform and what they do in the background. But without knowing this you don't even have an idea of how fast it will be. I also had such experience with Virtual Pascal where the FindFirst/ FindNext API functions are obscured by an extra layer to support multiple platforms (which I didn't know at first). I only wondered why my simple scan program for the creation date of files took 2 days on our server. After removing all the overhead by directly using FindFirst/FindNext from the windows API it boosted up to 6 hours only. Sure, many people don't care whether a program runs 2 days or 6 hours but I do. These are examples of bad underlying implementations. In both of these cases the implementation can probably be optimised to deliver close to maximal performance. The evolution to more and more abstraction is simply because there are more and more different underlying platforms, and because the days that most programmers were able to take full advantage of the underlying platform are long gone. With the moves to system and process virtual machines, many-cores, cloud computing, accelerators etc. this is only getting worse. Not to mention that going as low level as possible to get the last bit of performance will mean that you'll have to redo that work over and over again, unless you stay with one particular generation of one particular platform. Jonas___ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
