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Comment by moralestapia

17 hours ago

>The purpose of a ./configure script is basically to run the compiler a bunch of times and check which runs succeeded.

Wait is this true? (!)

9 comments

moralestapia

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gdwatson  16 hours ago

Historically, different Unixes varied a lot more than they do today. Say you want your program to use the C library function foo on platforms where it’s available and the function bar where it isn’t: You can write both versions and choose between them based on a C preprocessor macro, and the program will use the best option available for the platform where it was compiled.

But now the user has to set the preprocessor macro appropriately when he builds your program. Nobody wants to give the user a pop quiz on the intricacies of his C library every time he goes to install new software. So instead the developer writes a shell script that tries to compile a trivial program that uses function foo. If the script succeeds, it defines the preprocessor macro FOO_AVAILABLE, and the program will use foo; if it fails, it doesn’t define that macro, and the program will fall back to bar.

That shell script grew into configure. A configure script for an old and widely ported piece of software can check for a lot of platform features.

  • im3w1l  10 hours ago

    I'm not saying we should send everyone a docker container with a full copy of ubuntu, electron and foo.js whether they have foo in their c library or not, but maybe there is a middle ground?

    • moralestapia  10 hours ago

      I think this is a gigantic point in favor of interpreted languages.

      JS and Python wouldn't be what they are today if you had to `./configure` every website you want to visit, lmao.

      1 reply →

klysm  16 hours ago

The closer and deeper you look into the C toolchains the more grossed out you’ll be

  • acuozzo  15 hours ago

    Hands have to get dirty somewhere. "As deep as The Worker's City lay underground, so high above towered the City of Metropolis."

    The choices are:

    1. Restrict the freedom of CPU designers to some approximation of the PDP11. No funky DSP chips. No crazy vector processors.

    2. Restrict the freedom of OS designers to some approximation of Unix. No bespoke realtime OSes. No research OSes.

    3. Insist programmers use a new programming language for these chips and OSes. (This was the case prior to C and Unix.)

    4. Insist programmers write in assembly and/or machine code. Perhaps a macro-assembler is acceptable here, but this is inching toward C.

    The cost of this flexibility is gross tooling to make it manageable. Can it be done without years and years of accrued M4 and sh? Perhaps, but that's just CMake and CMake is nowhere near as capable as Autotools & friends are when working with legacy platforms.