4 ms·

It's funny the author uses an example of an array indexed by 199x values, as the 90s were in some way "the lost decade" of C/++ development, and an utter lack o

It's funny the author uses an example of an array indexed by 199x values, as the 90s were in some way "the lost decade" of C/++ development, and an utter lack of concern for this sort of checking. The realities of internet exposure put an end to this recklessness for casual^H^H^H^H^H "enterprise" software development. I love C A Hoare's comments, reference in this link (http://en.wikipedia.org/wiki/Bounds_checking http://en.wikipedia.org/wiki/Bounds_checking) about "some languages" (cough cough - C) Interesting how the Go language now includes array bounds checking. While 2 of the main designers are ex Bell labs, 1 of them is from U of Zurich. (I'm assuming he would have had some Pascal/Modula exposure there)

fexl 13y ago
I love C but I use it in a disciplined way. Here's the email I sent to the author: James: I liked your article on range checking. I'm very keen on assertions, for example here: https://github.com/chkoreff/Fexl/blob/fresh/base/src/buf.c#L30 https://github.com/chkoreff/Fexl/blob/fresh/base/src/buf.c#L... It's still fast as greased lightning. I buffer up 2.6 MB here: https://github.com/chkoreff/Fexl/blob/fresh/test/src/run.c#L399 https://github.com/chkoreff/Fexl/blob/fresh/test/src/run.c#L... It's too fast to notice. I can bump it up to 260 MB and try that: $ ./build && time ../bin/run : Buffering 260000000 bytes length = 260000000 real 0m1.751s user 0m1.608s sys 0m0.140s What the heck, let's try an even 2 GB: $ ./build && time ../bin/run Compile run Link run : Buffering 2000000000 bytes length = 2000000000 real 0m13.350s user 0m12.049s sys 0m1.288s Ah, but what if I remove my range check? $ ./build && time ../bin/run Compile buf Link run : Buffering 2000000000 bytes length = 2000000000 real 0m13.103s user 0m11.781s sys 0m1.312s Repeated testing of both ways shows no significant difference. I think I'll leave in the range check. Range checks also support one of my favorite programming maxims: No Silent Failure!
- deletes 13y ago
  How will assert help if the failure happens in production code? Wouldn't it be better if the error was logged to a file.
  - fexl 13y ago
    Assertion failure messages are sent to stderr. Production code can capture that as it wishes.
    - dllthomas 13y ago
      The assert from assert.h is a macro that completely elides the check if built with NDEBUG. Assuming you're not using some other assert(), and are building your production build with NDEBUG (which is typically part of what's meant by "a production build", though you can certainly disagree with the practice), production code cannot capture it as no messages will be generated.
      - Roboprog 13y ago
        For in-house code in a manufacturing company, we usually left all the debug symbol and assertions in our C code. For writing a product that shipped to others at a dev tools company, we usually turned off the debugging, turned on NDEBUG and full optimization. (although the product had checking for things built into its logic, and a lot of testing -- C being used as an assembler surrogate -- as we were writing developer tools, rather than "enterprise" whack-it-together-on-no-time-budget pile-age) "Production build" varies by environment, TMTOWTDI.
        dllthomas 13y ago
        Absolutely the case. I just think it's wrong to assume - without stating it - that NDEBUG will be off "in production".
      - fexl 13y ago
        Right now, in my code, assert(0==1) produces this output to stderr: run: run.c:422: main: Assertion `0==1' failed. Aborted That is what I want. You are correct. If I build with -DNDEBUG=1, then the assert is completely ignored: no error message, and no abort. That is not what I want. Therefore I will not build with -DNDEBUG=1. I will certainly not introduce "logging to a file" as a concept inside buf.c. There is no need for the pure data manipulation code in buf.c to know anything about files or stdio, or a specific name of a log file. If the assert from assert.h does not do what I want, then I'll make a version that does. However, that is a moot point, since right now it does what I want.

fexl 13y ago

I love C but I use it in a disciplined way. Here's the email I sent to the author: James: I liked your article on range checking. I'm very keen on assertions, for example here: https://github.com/chkoreff/Fexl/blob/fresh/base/src/buf.c#L30 https://github.com/chkoreff/Fexl/blob/fresh/base/src/buf.c#L... It's still fast as greased lightning. I buffer up 2.6 MB here: https://github.com/chkoreff/Fexl/blob/fresh/test/src/run.c#L399 https://github.com/chkoreff/Fexl/blob/fresh/test/src/run.c#L... It's too fast to notice. I can bump it up to 260 MB and try that: $ ./build && time ../bin/run : Buffering 260000000 bytes length = 260000000 real 0m1.751s user 0m1.608s sys 0m0.140s What the heck, let's try an even 2 GB: $ ./build && time ../bin/run Compile run Link run : Buffering 2000000000 bytes length = 2000000000 real 0m13.350s user 0m12.049s sys 0m1.288s Ah, but what if I remove my range check? $ ./build && time ../bin/run Compile buf Link run : Buffering 2000000000 bytes length = 2000000000 real 0m13.103s user 0m11.781s sys 0m1.312s Repeated testing of both ways shows no significant difference. I think I'll leave in the range check. Range checks also support one of my favorite programming maxims: No Silent Failure!

deletes 13y ago
How will assert help if the failure happens in production code? Wouldn't it be better if the error was logged to a file.
- fexl 13y ago
  Assertion failure messages are sent to stderr. Production code can capture that as it wishes.
  - dllthomas 13y ago
    The assert from assert.h is a macro that completely elides the check if built with NDEBUG. Assuming you're not using some other assert(), and are building your production build with NDEBUG (which is typically part of what's meant by "a production build", though you can certainly disagree with the practice), production code cannot capture it as no messages will be generated.
    - Roboprog 13y ago
      For in-house code in a manufacturing company, we usually left all the debug symbol and assertions in our C code. For writing a product that shipped to others at a dev tools company, we usually turned off the debugging, turned on NDEBUG and full optimization. (although the product had checking for things built into its logic, and a lot of testing -- C being used as an assembler surrogate -- as we were writing developer tools, rather than "enterprise" whack-it-together-on-no-time-budget pile-age) "Production build" varies by environment, TMTOWTDI.
      - dllthomas 13y ago
        Absolutely the case. I just think it's wrong to assume - without stating it - that NDEBUG will be off "in production".
    - fexl 13y ago
      Right now, in my code, assert(0==1) produces this output to stderr: run: run.c:422: main: Assertion `0==1' failed. Aborted That is what I want. You are correct. If I build with -DNDEBUG=1, then the assert is completely ignored: no error message, and no abort. That is not what I want. Therefore I will not build with -DNDEBUG=1. I will certainly not introduce "logging to a file" as a concept inside buf.c. There is no need for the pure data manipulation code in buf.c to know anything about files or stdio, or a specific name of a log file. If the assert from assert.h does not do what I want, then I'll make a version that does. However, that is a moot point, since right now it does what I want.