4 ms·

In this case, I'd look into compiling the existing code into .dll/.so files, and just linking between Extended Pascal and ${NEW_LANGUAGE}. Then, convert the c

by scj 8y ago

In this case, I'd look into compiling the existing code into .dll/.so files, and just linking between Extended Pascal and ${NEW_LANGUAGE}. Then, convert the code to ${NEW_LANGUAGE} as needed, if needed. That solution is probably the lowest cost / safest course... Assuming the Extended Pascal compiler they have supports it. But I suspect choosing D was a fait accompli.

Skunkleton 8y ago
This approach has always been the one that makes the most sense to me, but yet it also seems to be rare. I couldn't explain why.
_veelo 8y ago
This is the approach I took to modernise Fairway (which is just one component of our suite). It doesn't free us from the limitations of the Extended Pascal compiler. It still works, but we want a way out.
- scj 8y ago
  Hello, I assume by your username that you're the author! Transpiling is normally a little risky. Transpiling with a custom transpiler over ~500KLOC is downright terrifying. I'd be concerned that the cure is worse than the disease. I understand the allure of this solution. Bringing 30ish years of code into the modern era with a single piece of code sounds like a huge win. But you owe it to your employer (who seems really gracious and trusting) to ask: 1. Are there edge cases? Programmers are a clever bunch, and you can never be too sure about what features/bugs they've used/abused! 2. How will success of the transpile be determined? I'd use unit tests, but that'd take a lot of unit tests! 3. What % of that code path is critical? Can you get away with ensuring the functionality of a subset of the codebase? If so, could you just manually port that? 4. "Blaming the compiler" will be a reasonable excuse for any problem over the next year or two after deployment. I guarantee you'll be spending time proving that other peoples' mistakes are not your fault. How much flak are you and your boss going to take for this? 5. Since the code can be linked, might a more popular language (that will be known by a wider community) with a slow porting plan be reasonable? 6. Python is commonly used with scientific computing. Why does this case preclude it? If you are doing mostly numeric processing, that gets directly passed to the hardware anyway! You have been given a rare chance to pay down technical debt. From what I understand of your solution, I believe the bespoke transpiler and semi-known language will ultimately increase it. And I know you love D, but if I were brought in as a consultant, I'd be recommending the .dll/.so solution with Python. If something is really time sensitive, use Python binding to work with other languages (avoiding premature optimization). Even if myself or my fellow posters made a point that resonated, it might be too late for such discussions. I can't weigh the political costs for changing strategy now. So I'll wish you good luck, and hope that Extended Python doesn't have too many sharp edges for you to contend with. I hope to see a postmortem a few years from now detailing the outcome of this plan.
  - blub 8y ago
    Python has two big issues: performance and dynamic typing. The solution of using a HLL and dropping down to C for performance strikes me as overly optimistic: the only language where one can legitimately claim that it's pleasant to use C for extra performance is Objective-C. Anything else will be different degrees of painful. I didn't get the solution of using a dynamic lib and calling/extending that from Python. One would end up with 500kloc of Pascal and a Python one liner. All the work still happens in Pascal.
    - scj 8y ago
      I think there is an understanding that the whole situation is less than ideal. I'm proposing a low risk method to transition from the current situation to a healthy one over the long term. Having binary compatibility with the old version would be a great safety net while transitioning to another language. The main weakness of the author's plan, as the article explains it, is that they will be dealing with a lot of newly generated code at once (as well as an unknown number of unknowns). The plan would be fine if it was only ~10kloc, but ~500kloc is a very different beast! Come to think about it... It would be wise to have a "Plan B" still written in D, but linked to the binary rather than transpiled. That way if anything goes wrong after deployment, users can temporarily use that rather than revert to Extended Pascal. There probably isn't an easy solution for this problem. But maybe the author has found a silver bullet. I brought up Python because it sounds like SARC is adjacent to scientific computing, and it is likely they'd be able to pick up physics/math/engineering majors that are already familiar with Python. Plus, I bet they'd be able to use some really good Python libraries (possibly replacing some of that 500kloc custom code with open source libraries). The article makes it clear that naval architects (who are not expected to learn C++) are programming, so I doubt high performance computing is required in 100% of the code (at least I hope not). If there are genuine performance issues, tools alone won't save you, you need to hire programmers that know how to optimize (and they'll be fine writing C/C++ libraries with interfaces to Python). I strongly suspect the justification that interpreted languages don't meet performance requirements is more ideological than empirical. Besides, it's likely the existing binary will run faster than its transpiled descendant!

by scj 8y ago

Skunkleton 8y ago

This approach has always been the one that makes the most sense to me, but yet it also seems to be rare. I couldn't explain why.

_veelo 8y ago

This is the approach I took to modernise Fairway (which is just one component of our suite). It doesn't free us from the limitations of the Extended Pascal compiler. It still works, but we want a way out.

scj 8y ago
Hello, I assume by your username that you're the author! Transpiling is normally a little risky. Transpiling with a custom transpiler over ~500KLOC is downright terrifying. I'd be concerned that the cure is worse than the disease. I understand the allure of this solution. Bringing 30ish years of code into the modern era with a single piece of code sounds like a huge win. But you owe it to your employer (who seems really gracious and trusting) to ask: 1. Are there edge cases? Programmers are a clever bunch, and you can never be too sure about what features/bugs they've used/abused! 2. How will success of the transpile be determined? I'd use unit tests, but that'd take a lot of unit tests! 3. What % of that code path is critical? Can you get away with ensuring the functionality of a subset of the codebase? If so, could you just manually port that? 4. "Blaming the compiler" will be a reasonable excuse for any problem over the next year or two after deployment. I guarantee you'll be spending time proving that other peoples' mistakes are not your fault. How much flak are you and your boss going to take for this? 5. Since the code can be linked, might a more popular language (that will be known by a wider community) with a slow porting plan be reasonable? 6. Python is commonly used with scientific computing. Why does this case preclude it? If you are doing mostly numeric processing, that gets directly passed to the hardware anyway! You have been given a rare chance to pay down technical debt. From what I understand of your solution, I believe the bespoke transpiler and semi-known language will ultimately increase it. And I know you love D, but if I were brought in as a consultant, I'd be recommending the .dll/.so solution with Python. If something is really time sensitive, use Python binding to work with other languages (avoiding premature optimization). Even if myself or my fellow posters made a point that resonated, it might be too late for such discussions. I can't weigh the political costs for changing strategy now. So I'll wish you good luck, and hope that Extended Python doesn't have too many sharp edges for you to contend with. I hope to see a postmortem a few years from now detailing the outcome of this plan.
- blub 8y ago
  Python has two big issues: performance and dynamic typing. The solution of using a HLL and dropping down to C for performance strikes me as overly optimistic: the only language where one can legitimately claim that it's pleasant to use C for extra performance is Objective-C. Anything else will be different degrees of painful. I didn't get the solution of using a dynamic lib and calling/extending that from Python. One would end up with 500kloc of Pascal and a Python one liner. All the work still happens in Pascal.
  - scj 8y ago
    I think there is an understanding that the whole situation is less than ideal. I'm proposing a low risk method to transition from the current situation to a healthy one over the long term. Having binary compatibility with the old version would be a great safety net while transitioning to another language. The main weakness of the author's plan, as the article explains it, is that they will be dealing with a lot of newly generated code at once (as well as an unknown number of unknowns). The plan would be fine if it was only ~10kloc, but ~500kloc is a very different beast! Come to think about it... It would be wise to have a "Plan B" still written in D, but linked to the binary rather than transpiled. That way if anything goes wrong after deployment, users can temporarily use that rather than revert to Extended Pascal. There probably isn't an easy solution for this problem. But maybe the author has found a silver bullet. I brought up Python because it sounds like SARC is adjacent to scientific computing, and it is likely they'd be able to pick up physics/math/engineering majors that are already familiar with Python. Plus, I bet they'd be able to use some really good Python libraries (possibly replacing some of that 500kloc custom code with open source libraries). The article makes it clear that naval architects (who are not expected to learn C++) are programming, so I doubt high performance computing is required in 100% of the code (at least I hope not). If there are genuine performance issues, tools alone won't save you, you need to hire programmers that know how to optimize (and they'll be fine writing C/C++ libraries with interfaces to Python). I strongly suspect the justification that interpreted languages don't meet performance requirements is more ideological than empirical. Besides, it's likely the existing binary will run faster than its transpiled descendant!