tutorials: improve c2v tutorial a bit
Alexander Medvednikov
GitHub
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@ -10,6 +10,8 @@ https://www.youtube.com/watch?v=6oXrz3oRoEg
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Let's start.
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### A simple C program
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First, We have a simple C program that prints prime numbers. It's a small program,
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but it has some of the most widely used language features:
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function definitions, control flow via for loops and if conditions, a libc function call,
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@ -77,6 +79,7 @@ translated code all blocks are explicitely marked with brackets.
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C2V successfully converts C's bool type to V's bool.
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### Wrapper generation
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C2V also has a wrapper generation mode.
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@ -128,7 +131,7 @@ clean wrapper functions that can be called with `usersapi.create_user()` instead
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Perhaps in the future C2V will translate C strings (char pointers) to V strings as well.
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### Translating DOOM
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All right, this works, and it's nice, but these are very trivial examples.
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Let's try something a lot more fun, like the DOOM game.
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@ -139,20 +142,21 @@ of the tools but also to have something to test via CI to avoid regressions.
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During V's release we had lots of various examples, now for C2V we have DOOM.
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This is the primary test of C2V.
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DOOM is a very complex project that uses some really tricky elements of the C language.
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And making sure C2V can always handle DOOM not only serves as a good C2V test but also
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as a test of the V compiler itself, since it can run entire DOOM in pure V.
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First let's download the DOOM source and build it to make sure everything works.
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The original 1997 open source release doesn't work nicely on modern OSs, so the community
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has been working on different forks. I'll be using Chocolate Doom, it's one of the most
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popular forks, and its goal is to be as close to the original as possible
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(they even keep the original bugs).
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```bash
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git clone https://github.com/vlang/doom
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```
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The main difference in this fork is using SDL for cross platform rendering, so we'll need
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to install SDL2 before we can build it.
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@ -163,7 +167,6 @@ into a single executable.
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To build the C version:
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```bash
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git clone https://github.com/vlang/doom
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cd doom/chocolate-doom
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cmake .
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make chocolate-doom
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@ -192,27 +195,19 @@ This creates a new directory `src/doom/doom_v/`.
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And we can use any name we want, there's a c2v configuration file.
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`ls -alh src/doom/doom_v`
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`ll src/doom/doom_v`
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It has a bunch of files translated from C to V.
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We can open any file, for example g_game.c and verify that it is indeed DOOM code
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translated from C to V. It's also been nicely formatted by vfmt.
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Now let's build it.
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```bash
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cd src/doom
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sh build_doom_v.sh
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```
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I'll explain what we have in the shell script a bit later.
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@ -228,11 +223,6 @@ and forcing a re-render.
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There's a bug somewhere in C2V, it has just been released and needs some fixes.
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Now let's look at those shell scripts and see how we built the V translation of DOOM.
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C2V doesn't understand makefiles yet, so we have to do things manually.
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@ -295,12 +285,7 @@ some V specific code, like a reversed V array.
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Let's rebuild it and run again. As expected, we're getting our array printed every time an
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enemy moves.
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### Replacing C with V file by file
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We translated the entire project. But sometimes it may be better to do more gradual transition
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from C to V. For example, if you want to move your project from C to V, you might prefer doing
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@ -327,14 +312,18 @@ processes. From C to V via C2V and then From V back to C again via the V compile
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In fact we can actually look at the generated C code after all the translation and compare it
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to the original. Very clean and barely changed:
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Both C2V and V generate clean human readable code.
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https://twitter.com/v_language/status/1531816534011682821
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The comments and C defines are missing right now, that's obviously something very nice to have,
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so they will be translated as well.
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### Conclusion
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C2V has just been released on June 22th 2022, so it's going to mature with the help of
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the community. With bug fixes and new C features supported, it should support the
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entire C standard soon.
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