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ci: separate workflow for docs line len check (#6653)

pull/6659/head
Lukas Neubert 2020-10-20 20:14:56 +02:00 committed by GitHub
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5 changed files with 194 additions and 103 deletions
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22
.github/workflows/ci.yml vendored
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@ -1,7 +1,16 @@
name: CI
on: [push, pull_request]
jobs:
on:
push:
paths-ignore:
- "doc/**"
- "CHANGELOG.md"
pull_request:
paths-ignore:
- "doc/**"
- "CHANGELOG.md"
jobs:
code-formatting:
runs-on: ubuntu-18.04
env:
@ -461,15 +470,6 @@ jobs:
# - name: v2 self compilation
# run: .\v.exe -o v2.exe cmd/v && .\v2.exe -o v3.exe cmd/v
docs-line-len-check:
runs-on: ubuntu-18.04
steps:
- uses: actions/checkout@v2
- name: Build
run: make
- name: Check docs line length
run: ./v run cmd/tools/check-md.v doc/docs.md CHANGELOG.md
compilable-v-c-and-v-win-c:
runs-on: ubuntu-latest

23
.github/workflows/docs_ci.yml vendored 100644
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@ -0,0 +1,23 @@
name: Docs CI
on:
push:
paths:
- "cmd/tools/check-md.v"
- "doc/**"
- "CHANGELOG.md"
pull_request:
paths:
- "cmd/tools/check-md.v"
- "doc/**"
- "CHANGELOG.md"
jobs:
docs-line-len-check:
runs-on: ubuntu-18.04
steps:
- uses: actions/checkout@v2
- name: Build V
run: make
- name: Check docs line length
run: ./v run cmd/tools/check-md.v doc/docs.md doc/upcoming.md CHANGELOG.md

44
CHANGELOG.md
View File

@ -1,7 +1,8 @@
## V 0.1.27
*5 May 2020*
- vfmt has been re-written from scratch using the new AST parser. It's much faster, cleaner, and can format
- vfmt has been re-written from scratch using the new AST parser.
It's much faster, cleaner, and can format
files with compilation errors.
- `strconv`, `sprintf`, and `printf` in native V, without any libc calls.
- Interfaces are now a lot more stable and have all expected features.
@ -10,13 +11,13 @@ files with compilation errors.
- New `[]int{cap:cap, len:len}` syntax for initializing array length and capacity.
- New `is` keyword for checking the type of sum types and interfaces.
- `as` can now be used to cast interfaces and sum types.
- Profiling with `-profile`. Prints a nice table with detailed information about every single function call:
number of calls, average time per call, total time per function.
- Profiling with `-profile`. Prints a nice table with details about every single function call:
number of calls, average time per call, total time per function
- `import(xxx)` syntax has been removed in favor of `import xxx` for simplicity and greppability.
- Lots of fixes and improvements in the type checker.
- `time.StopWatch`
- `dl` module for dynamic loading.
- Automatic `str()` method generation for every single type, including all arrays and fixed size arrays.
- Automatic `str()` method generation for every single type, including all arrays.
- Short struct initialization syntax for imitating named function args: `foo(bar:0, baz:1)`.
- New operator `!in`.
- Performance improvements in critical parts of the builtin data structures (array, map).
@ -37,13 +38,15 @@ number of calls, average time per call, total time per function.
## V 0.1.25
*1 Apr 2020*
- The entire compiler has been re-written with an AST parser. The code is now a lot cleaner and more maintainable. ~15k lines of old compiler code were removed.
- The entire compiler has been re-written with an AST parser.
The code is now a lot cleaner and more maintainable.
~15k lines of old compiler code were removed.
## V 0.1.24
*31 Dec 2019*
- A new parser/generator built on top of an AST that simplifies code greatly and allows to implement new
backends much faster.
- A new parser/generator built on top of an AST that simplifies code greatly
and allows to implement new backends much faster.
- Sum types (`type Expr = IfExpr | MatchExpr | IntegerLiteral`).
- B-tree map (sped up the V compiler by ~10%).
- `v fmt -w`.
@ -54,7 +57,7 @@ number of calls, average time per call, total time per function.
- os: `is_link()`, `is_dir()`, `exists()`.
- Ranging through fixed size arrays.
- Lots of fixes in ORM and vweb.
- The first tutorial: [building a simple web application with vweb](https://github.com/vlang/v/blob/master/tutorials/building-a-simple-web-blog-with-vweb.md).
- The first tutorial: [building a simple web application with vweb](https://github.com/vlang/v/blob/master/tutorials/building-a-simple-web-blog-with-vweb.md)
- Match expressions now must be exhaustive.
- freestanding: `malloc()`/`free()`.
- `++` is now required instead of `+= 1` for consistency.
@ -76,13 +79,14 @@ number of calls, average time per call, total time per function.
## V 0.1.23
*30 Nov 2019*
- [Direct x64 machine code generation](https://github.com/vlang/v/issues/2849). Hello world being built in 3 milliseconds.
- Bare metal support via the `-freestanding` flag, allowing to build programs without linking to libc.
- [Direct x64 machine code generation](https://github.com/vlang/v/issues/2849).
Hello world being built in 3 milliseconds.
- Bare metal support via the `-freestanding` flag, to build programs without linking to libc.
- Prebuilt V packages for Linux, macOS, and Windows.
- `string.index()` now returns `?int` instead of `int/-1`.
- Lots of fixes in Generics.
- vweb framework for developing web applications is back.
- Vorum, the forum/blogging software written in V/vweb, can now be compiled and has been added to CI.
- Vorum, the forum/blogging software written in vweb, can now be compiled and has been added to CI.
- REPL, `v up` have been split up into separate applications to keep the core V compiler small.
- V now enforces short enum syntax (`.green` instead of `Color.green`) when it's enough.
- V UI for macOS.
@ -90,7 +94,8 @@ number of calls, average time per call, total time per function.
- `os.cp()` for copying files and directores.
- Additional compile-time flags: `$if clang, msvc, mingw, x32, x64, big_endian, little_endian {`.
- All C functions now have to be declared, all missing C functions have been defined.
- Global variables (only with the `--enable-globals` flag) for low level applications like kernels and drivers.
- Global variables (only with the `--enable-globals` flag)
for low level applications like kernels and drivers.
- Nothing can be cast to bool (previously code like `if bool(1) {` worked).
- `<<` and `>>` now work with all integer types.
- V detects Cygwin and shows an error (V supports Windows natively).
@ -116,7 +121,7 @@ number of calls, average time per call, total time per function.
- `malloc/free` on bare metal.
- `utf8` helper functions (`to_lower()`, `to_upper()`, etc).
- Optimization of `for c in str {`.
- `string/array.left/right/slice/substr` were removed (`[a..b]` slicing syntax should be used instead).
- `string/array.left/right/slice/substr` were removed (use `[a..b]` slicing syntax instead).
@ -128,8 +133,7 @@ number of calls, average time per call, total time per function.
- Optimized `array.filter()` and `array.map()`.
- `sqlite` module.
- Cached modules for faster compilation.
- Dramatic compilation optimizations: [V now compiles itself in
0.10 - 0.30 seconds](https://github.com/vlang/v/wiki/The-V-language-now-compiles-itself-in-0.09-seconds).
- Dramatic compilation optimizations: [V now compiles itself in 0.10 - 0.30 seconds](https://github.com/vlang/v/wiki/The-V-language-now-compiles-itself-in-0.09-seconds)
- V scripts (simpler and cross-platform alternative to Bash).
- Infinite multi-dimensional arrays (`[][][]int`).
- `unsafe`.
@ -296,7 +300,7 @@ this backend.
## V 0.1.15
*15 Jul 2019*
- FreeBSD, OpenBSD, NetBSD, DragonFly support.
- Hot code reloading now works with graphical applications: [bounce.v](https://github.com/vlang/v/blob/master/examples/hot_code_reloading/bounce.v).
- Hot reloading now works with graphical applications: [bounce.v](examples/hot_reload/bounce.v)
- VROOT was removed, the installation process is now much simpler.
- `defer` statement.
- map.v was re-written. It's now much faster.
@ -310,7 +314,7 @@ this backend.
## V 0.1.14
*12 Jul 2019*
- `gg` module Windows support, V Tetris runs on Windows.
- `glad` and `cJSON` are now compiled only once, this makes compilation of programs using `gg` and `json` a bit faster.
- Compile `glad` and `cJSON` only once. Programs using `gg` or `json` compile a bit faster.
- `v.c` has been cleaned up and minimized (~16k => ~10k lines of code).
- `type` aliases can now have methods.
- Const overflow check during compilation (`byte(1000)` will no longer compile).
@ -332,8 +336,10 @@ this backend.
## V 0.1.12
*4 Jul 2019*
- V can finally compile itself on Windows (https://github.com/vlang/v#mingw-w64).
- `os` module now uses optionals in all functions that return `File`. Lots of bugs with optionals fixed.
- `println` was optimized. It no longer results in allocations. Now it also works correctly with all integer types.
- `os` module now uses optionals in all functions that return `File`.
- Lots of bugs with optionals were fixed.
- `println` was optimized. It no longer results in allocations.
Now it also works correctly with all integer types.
- Lots of `vfmt` fixes, it will be enabled tomorrow.
- New `strings` module.
- Lots of other fixes and improvements, thanks to all the contributors.

21
cmd/tools/check-md.v
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@ -8,23 +8,36 @@ const (
fn main() {
files_paths := os.args[1..]
mut warnings := 0
mut errors := 0
for file_path in files_paths {
real_path := os.real_path(file_path)
lines := os.read_lines(real_path) or {
println('"$file_path" does not exist')
warnings++
continue
}
for i, line in lines {
if line.len > too_long_line_length {
eprintln('$real_path:${i+1}:${line.len+1}: line too long')
linetrace_msg := '$file_path:${i + 1}:${line.len + 1}: '
if line.starts_with('|') {
println(linetrace_msg + 'long table (warn)')
warnings++
} else if line.contains('https') {
println(linetrace_msg + 'long link (warn)')
warnings++
} else {
eprintln(linetrace_msg + 'line too long')
errors++
}
}
}
// TODO: uncomment this AFTER doc/docs.md line lengths are fixed
/*
}
if warnings > 0 || errors > 0 {
println('\nWarnings | Errors')
println('$warnings\t | $errors')
}
if errors > 0 {
exit(1)
}
*/
}

185
doc/docs.md
View File

@ -255,7 +255,8 @@ println(age)
```
To change the value of the variable use `=`. In V, variables are
immutable by default. To be able to change the value of the variable, you have to declare it with `mut`.
immutable by default.
To be able to change the value of the variable, you have to declare it with `mut`.
Try compiling the program above after removing `mut` from the first line.
@ -281,8 +282,10 @@ fn main() {
### Declaration errors
In development mode the compiler will warn you that you haven't used the variable (you'll get an "unused variable" warning).
In production mode (enabled by passing the `-prod` flag to v – `v -prod foo.v`) it will not compile at all (like in Go).
In development mode the compiler will warn you that you haven't used the variable
(you'll get an "unused variable" warning).
In production mode (enabled by passing the `-prod` flag to v – `v -prod foo.v`)
it will not compile at all (like in Go).
```v
fn main() {
@ -294,7 +297,8 @@ fn main() {
}
```
Unlike most languages, variable shadowing is not allowed. Declaring a variable with a name that is already used in a parent scope will cause a compilation error.
Unlike most languages, variable shadowing is not allowed. Declaring a variable with a name
that is already used in a parent scope will cause a compilation error.
## Types
@ -393,8 +397,9 @@ println('Hello, $name!') // Hello, Bob!
It also works with fields: `'age = $user.age'`.
If you need more complex expressions, use `${}`: `'can register = ${user.age > 13}'`.
Format specifiers similar to those in C's `printf()` are also supported. `f`, `g`, `x`, etc. are optional
and specify the output format. The compiler takes care of the storage size, so there is no `hd` or `llu`.
Format specifiers similar to those in C's `printf()` are also supported.
`f`, `g`, `x`, etc. are optional and specify the output format.
The compiler takes care of the storage size, so there is no `hd` or `llu`.
```v
x := 123.4567
@ -503,8 +508,10 @@ The type of an array is determined by the first element:
* `[1, 2, 3]` is an array of ints (`[]int`).
* `['a', 'b']` is an array of strings (`[]string`).
If V is unable to infer the type of an array, the user can explicitly specify it for the first element: `[byte(16), 32, 64, 128]`.
V arrays are homogeneous (all elements must have the same type). This means that code like `[1, 'a']` will not compile.
If V is unable to infer the type of an array,
the user can explicitly specify it for the first element: `[byte(16), 32, 64, 128]`.
V arrays are homogeneous (all elements must have the same type).
This means that code like `[1, 'a']` will not compile.
The `.len` field returns the length of the array. Note that it's a read-only field,
and it can't be modified by the user. Exported fields are read-only by default in V.
@ -543,7 +550,8 @@ and the default element (`init`):
arr := []int{ len: 5, init: -1 } // `[-1, -1, -1, -1, -1]`
```
Setting the capacity improves performance of insertions, as it reduces the number of reallocations needed:
Setting the capacity improves performance of insertions,
as it reduces the number of reallocations needed:
```v
mut numbers := []int{ cap: 1000 }
@ -731,7 +739,8 @@ if a < b {
```
`if` statements are pretty straightforward and similar to most other languages.
Unlike other C-like languages, there are no parentheses surrounding the condition, and the braces are always required.
Unlike other C-like languages,
there are no parentheses surrounding the condition and the braces are always required.
`if` can be used as an expression:
@ -767,7 +776,8 @@ if x is Abc {
If you have a struct field which should be checked, there is also a way to name a alias.
```v
if x.bar is MyStruct as bar {
// x.bar cannot be cast automatically, you must explicitly state "as bar" to create a variable with the MyStruct type
// x.bar cannot be cast automatically
// you must explicitly state "as bar" to create a variable with the MyStruct type
println(bar)
}
```
@ -797,7 +807,8 @@ if parser.token in [.plus, .minus, .div, .mult] {
}
```
V optimizes such expressions, so both `if` statements above produce the same machine code and no arrays are created.
V optimizes such expressions,
so both `if` statements above produce the same machine code and no arrays are created.
### For loop
@ -819,7 +830,8 @@ for i, name in names {
The `for value in arr` form is used for going through elements of an array.
If an index is required, an alternative form `for index, value in arr` can be used.
Note, that the value is read-only. If you need to modify the array while looping, you have to use indexing:
Note, that the value is read-only.
If you need to modify the array while looping, you have to use indexing:
```v
mut numbers := [0, 1, 2]
@ -982,7 +994,8 @@ Note: `match` as an expression is not usable in `for` loop and `if` statements.
### Defer
A defer statement defers the execution of a block of statements until the surrounding function returns.
A defer statement defers the execution of a block of statements
until the surrounding function returns.
```v
fn read_log() {
@ -1061,7 +1074,8 @@ struct Foo {
}
```
All struct fields are zeroed by default during the creation of the struct. Array and map fields are allocated.
All struct fields are zeroed by default during the creation of the struct.
Array and map fields are allocated.
It's also possible to define custom default values.
@ -1158,7 +1172,8 @@ fn main() {
}
```
This means that defining public readonly fields is very easy in V, no need in getters/setters or properties.
This means that defining public readonly fields is very easy in V,
no need in getters/setters or properties.
### Methods
@ -1190,11 +1205,11 @@ but a short, preferably one letter long, name.
### Pure functions by default
V functions are pure by default, meaning that their return values are a function of their arguments only,
and their evaluation has no side effects (besides I/O).
V functions are pure by default, meaning that their return values are a function of their
arguments only, and their evaluation has no side effects (besides I/O).
This is achieved by a lack of global variables and all function arguments being immutable by default,
even when [references](#references) are passed.
This is achieved by a lack of global variables and all function arguments being
immutable by default, even when [references](#references) are passed.
V is not a purely functional language however.
@ -1243,7 +1258,8 @@ It is preferable to return values instead of modifying arguments.
Modifying arguments should only be done in performance-critical parts of your application
to reduce allocations and copying.
For this reason V doesn't allow the modification of arguments with primitive types such as integers. Only more complex types such as arrays and maps may be modified.
For this reason V doesn't allow the modification of arguments with primitive types (e.g. integers).
Only more complex types such as arrays and maps may be modified.
Use `user.register()` or `user = register(user)`
instead of `register(mut user)`.
@ -1542,7 +1558,8 @@ match color {
```
Enum match must be exhaustive or have an `else` branch. This ensures that if a new enum field is added, it's handled everywhere in the code.
Enum match must be exhaustive or have an `else` branch.
This ensures that if a new enum field is added, it's handled everywhere in the code.
### Sum types
@ -1673,7 +1690,8 @@ V combines `Option` and `Result` into one type, so you don't need to decide whic
The amount of work required to "upgrade" a function to an optional function is minimal;
you have to add a `?` to the return type and return an error when something goes wrong.
If you don't need to return an error message, you can simply `return none` (this is a more efficient equivalent of `return error("")`).
If you don't need to return an error message, you can simply `return none`
(this is a more efficient equivalent of `return error("")`).
This is the primary mechanism for error handling in V. They are still values, like in Go,
but the advantage is that errors can't be unhandled, and handling them is a lot less verbose.
@ -1728,16 +1746,18 @@ user := repo.find_user_by_id(7) or {
}
```
Here, you can either call `panic()` or `exit()`, which will stop the execution of the entire program,
or use a control flow statement (`return`, `break`, `continue`, etc) to break from the current block.
Here, you can either call `panic()` or `exit()`, which will stop the execution of the
entire program, or use a control flow statement (`return`, `break`, `continue`, etc)
to break from the current block.
Note that `break` and `continue` can only be used inside a `for` loop.
V does not have a way to forcibly "unwrap" an optional (as other languages do, for instance Rust's `unwrap()`
or Swift's `!`). To do this, use `or { panic(err) }` instead.
V does not have a way to forcibly "unwrap" an optional (as other languages do,
for instance Rust's `unwrap()` or Swift's `!`). To do this, use `or { panic(err) }` instead.
---
The third method is to provide a default value at the end of the `or` block. In case of an error,
that value would be assigned instead, so it must have the same type as the content of the `Option` being handled.
The third method is to provide a default value at the end of the `or` block.
In case of an error, that value would be assigned instead,
so it must have the same type as the content of the `Option` being handled.
```v
fn do_something(s string) ?string {
@ -1911,8 +1931,9 @@ y := <-ch2 ?
#### Channel Select
The `select` command allows monitoring several channels at the same time without noticeable CPU load. It consists
of a list of possible transfers and associated branches of statements - similar to the [match](#match) command:
The `select` command allows monitoring several channels at the same time
without noticeable CPU load. It consists of a list of possible transfers and associated branches
of statements - similar to the [match](#match) command:
```v
select {
a := <-ch {
@ -1934,7 +1955,8 @@ The timeout branch is optional. If it is absent `select` waits for an unlimited
It is also possible to proceed immediately if no channel is ready in the moment `select` is called
by adding an `else { ... }` branch. `else` and `> timeout` are mutually exclusive.
The `select` command can be used as an *expression* of type `bool` that becomes `false` if all channels are closed:
The `select` command can be used as an *expression* of type `bool`
that becomes `false` if all channels are closed:
```v
if select {
ch <- a {
@ -1956,14 +1978,15 @@ res2 := ch2.try_pop(mut b) // try to perform `b = <-ch2
l := ch.len // number of elements in queue
c := ch.cap // maximum queue length
```
The `try_push/pop()` methods will return immediately with one of the results `.success`, `.not_ready`
or `.closed` - dependent on whether the object has been transferred or the reason why not. Usage
of these methods and properties in production is not recommended - algorithms based on them are often subject
to race conditions. Use `select` instead.
The `try_push/pop()` methods will return immediately with one of the results
`.success`, `.not_ready` or `.closed` - dependent on whether the object has been transferred or
the reason why not.
Usage of these methods and properties in production is not recommended -
algorithms based on them are often subject to race conditions. Use `select` instead.
Data can be exchanged between a coroutine
and the calling thread via a shared variable. This variable should be created as reference and passed to
the coroutine as `mut`. The underlying `struct` should also contain a `mutex` to lock concurrent access:
Data can be exchanged between a coroutine and the calling thread via a shared variable.
This variable should be created as reference and passed to the coroutine as `mut`.
The underlying `struct` should also contain a `mutex` to lock concurrent access:
```v
import sync
@ -2035,10 +2058,12 @@ println(foos[1].x)
Because of the ubiquitous nature of JSON, support for it is built directly into V.
The `json.decode` function takes two arguments: the first argument of the `json.decode` function is the type into which the JSON value should be decoded and the second is a string containing the JSON data.
The `json.decode` function takes two arguments:
the first is the type into which the JSON value should be decoded and
the second is a string containing the JSON data.
V generates code for JSON encoding and decoding. No runtime reflection is used. This results in much better
performance.
V generates code for JSON encoding and decoding.
No runtime reflection is used. This results in much better performance.
## Testing
@ -2153,7 +2178,8 @@ fn test() []int {
(This is still in an alpha state)
V has a built-in ORM (object-relational mapping) which supports SQLite, and will soon support MySQL, Postgres, MS SQL, and Oracle.
V has a built-in ORM (object-relational mapping) which supports SQLite,
and will soon support MySQL, Postgres, MS SQL, and Oracle.
V's ORM provides a number of benefits:
@ -2161,7 +2187,8 @@ V's ORM provides a number of benefits:
- Queries are constructed using V's syntax. (There's no need to learn another syntax.)
- Safety. (All queries are automatically sanitised to prevent SQL injection.)
- Compile time checks. (This prevents typos which can only be caught during runtime.)
- Readability and simplicity. (You don't need to manually parse the results of a query and then manually construct objects from the parsed results.)
- Readability and simplicity. (You don't need to manually parse the results of a query and
then manually construct objects from the parsed results.)
```v
struct Customer { // struct name has to be the same as the table name (for now)
@ -2199,7 +2226,8 @@ For more examples, see <a href='https://github.com/vlang/v/blob/master/vlib/orm/
## Writing Documentation
The way it works is very similar to Go. It's very simple: there's no need to
write documentation separately for your code, vdoc will generate it from docstrings in the source code.
write documentation separately for your code,
vdoc will generate it from docstrings in the source code.
Documentation for each function/type/const must be placed right before the declaration:
@ -2335,8 +2363,10 @@ fn my_callback(arg voidptr, howmany int, cvalues &charptr, cnames &charptr) int
fn main() {
db := &C.sqlite3(0) // this means `sqlite3* db = 0`
C.sqlite3_open('users.db', &db) // passing a string literal to a C function call results in a C string, not a V string
// C.sqlite3_open(db_path.str, &db) // you can also use `.str byteptr` field to convert a V string to a C char pointer
// passing a string literal to a C function call results in a C string, not a V string
C.sqlite3_open('users.db', &db)
// C.sqlite3_open(db_path.str, &db)
// you can also use `.str byteptr` field to convert a V string to a C char pointer
query := 'select count(*) from users'
stmt := &C.sqlite3_stmt(0)
C.sqlite3_prepare_v2(db, query.str, - 1, &stmt, 0)
@ -2365,7 +2395,8 @@ Add `#flag` directives to the top of your V files to provide C compilation flags
- `-L` for adding C library files search paths
- `-D` for setting compile time variables
You can use different flags for different targets. Currently the `linux`, `darwin` , `freebsd`, and `windows` flags are supported.
You can use different flags for different targets.
Currently the `linux`, `darwin` , `freebsd`, and `windows` flags are supported.
NB: Each flag must go on its own line (for now)
@ -2379,7 +2410,9 @@ NB: Each flag must go on its own line (for now)
### Including C code
You can also include C code directly in your V module. For example, let's say that your C code is located in a folder named 'c' inside your module folder. Then:
You can also include C code directly in your V module.
For example, let's say that your C code is located in a folder named 'c' inside your module folder.
Then:
* Put a v.mod file inside the toplevel folder of your module (if you
created your module with `v new` you already have v.mod file). For
@ -2401,11 +2434,13 @@ Module {
#include "header.h"
```
NB: @VROOT will be replaced by V with the *nearest parent folder, where there is a v.mod file*.
Any .v file beside or below the folder where the v.mod file is, can use `#flag @VROOT/abc` to refer to this folder.
The @VROOT folder is also *prepended* to the module lookup path, so you can *import* other
modules under your @VROOT, by just naming them.
Any .v file beside or below the folder where the v.mod file is,
can use `#flag @VROOT/abc` to refer to this folder.
The @VROOT folder is also *prepended* to the module lookup path,
so you can *import* other modules under your @VROOT, by just naming them.
The instructions above will make V look for an compiled .o file in your module `folder/c/implementation.o`.
The instructions above will make V look for an compiled .o file in
your module `folder/c/implementation.o`.
If V finds it, the .o file will get linked to the main executable, that used the module.
If it does not find it, V assumes that there is a `@VROOT/c/implementation.c` file,
and tries to compile it to a .o file, then will use that.
@ -2416,15 +2451,19 @@ You can see a complete minimal example for using C code in a V wrapper module he
Another example, demonstrating passing structs from C to V and back again:
[interoperate between C to V to C](https://github.com/vlang/v/tree/master/vlib/v/tests/project_with_c_code_2).
You can use `-cflags` to pass custom flags to the backend C compiler. You can also use `-cc` to change the default C backend compiler.
You can use `-cflags` to pass custom flags to the backend C compiler.
You can also use `-cc` to change the default C backend compiler.
For example: `-cc gcc-9 -cflags -fsanitize=thread`.
### C types
Ordinary zero terminated C strings can be converted to V strings with `string(cstring)` or `string(cstring, len)`.
Ordinary zero terminated C strings can be converted to V strings with `string(cstring)`
or `string(cstring, len)`.
NB: Each `string(...)` function does NOT create a copy of the `cstring`, so you should NOT free it after calling `string()`. If you need to make a copy of the C string (some libc APIs like `getenv` pretty much require that, since they
return pointers to internal libc memory), you can use `cstring_to_vstring(cstring)`.
NB: Each `string(...)` function does NOT create a copy of the `cstring`,
so you should NOT free it after calling `string()`.
If you need to make a copy of the C string (some libc APIs like `getenv` pretty much require that,
since they return pointers to internal libc memory), you can use `cstring_to_vstring(cstring)`.
On Windows, C APIs often return so called `wide` strings (utf16 encoding).
These can be converted to V strings with `string_from_wide(&u16(cwidestring))` .
@ -2449,13 +2488,19 @@ To debug issues in the generated C code, you can pass these flags:
- `-cg` - produces a less optimized executable with more debug information in it.
- `-showcc` - prints the C command that is used to build the program.
For the best debugging experience, you can pass all of them at the same time: `v -cg -showcc yourprogram.v` , then just run your debugger (gdb/lldb) or IDE on the produced executable `yourprogram`.
For the best debugging experience, you can pass all of them at the same time:
`v -cg -showcc yourprogram.v`,
then just run your debugger (gdb/lldb) or IDE on the produced executable `yourprogram`.
If you just want to inspect the generated C code, without further compilation, you can also use the `-o` flag (e.g. `-o file.c`). This will make V produce the `file.c` then stop.
If you just want to inspect the generated C code,
without further compilation, you can also use the `-o` flag (e.g. `-o file.c`).
This will make V produce the `file.c` then stop.
If you want to see the generated C source code for *just* a single C function, for example `main`, you can use: `-printfn main -o file.c` .
If you want to see the generated C source code for *just* a single C function,
for example `main`, you can use: `-printfn main -o file.c`.
To see a detailed list of all flags that V supports, use `v help`, `v help build`, `v help build-c` .
To see a detailed list of all flags that V supports,
use `v help`, `v help build` and `v help build-c`.
## Conditional compilation
@ -2513,7 +2558,8 @@ Full list of builtin options:
## Compile time pseudo variables
V also gives your code access to a set of pseudo string variables, that are substituted at compile time:
V also gives your code access to a set of pseudo string variables,
that are substituted at compile time:
- `@FN` => replaced with the name of the current V function
- `@MOD` => replaced with the name of the current V module
@ -2641,9 +2687,9 @@ fn main() {
}
```
Operator overloading goes against V's philosophy of simplicity and predictability. But since
scientific and graphical applications are among V's domains, operator overloading is an important feature to have
in order to improve readability:
Operator overloading goes against V's philosophy of simplicity and predictability.
But since scientific and graphical applications are among V's domains,
operator overloading is an important feature to have in order to improve readability:
`a.add(b).add(c.mul(d))` is a lot less readable than `a + b + c * d`.
@ -2705,11 +2751,13 @@ An online C/C++ to V translator is coming soon.
When should you translate C code and when should you simply call C code from V?
If you have well-written, well-tested C code, then of course you can always simply call this C code from V.
If you have well-written, well-tested C code,
then of course you can always simply call this C code from V.
Translating it to V gives you several advantages:
- If you plan to develop that code base, you now have everything in one language, which is much safer and easier to develop in than C.
- If you plan to develop that code base, you now have everything in one language,
which is much safer and easier to develop in than C.
- Cross-compilation becomes a lot easier. You don't have to worry about it at all.
- No more build flags and include files either.
@ -2812,7 +2860,8 @@ On Unix-like platforms, the file can be run directly after making it executable
V has several attributes that modify the behavior of functions and structs.
An attribute is specified inside `[]` right before a function/struct declaration and applies only to the following declaration.
An attribute is specified inside `[]` right before a function/struct declaration
and applies only to the following declaration.
```v
// Calling this function will result in a deprecation warning