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doc: document x := ?int(none)

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Alexander Medvednikov 2024-05-20 21:47:50 +03:00
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doc/docs.md
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@ -2066,7 +2066,7 @@ from `low` up to *but not including* `high`.
> This exclusive range notation and zero-based indexing follow principles of
logical consistency and error reduction. As Edsger W. Dijkstra outlines in
'Why Numbering Should Start at Zero'
([EWD831](https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html)),
([EWD831](https://www.cs.utexas.edu/users/EWD/transcriptions/EWD08xx/EWD831.html)),
zero-based indexing aligns the index with the preceding elements in a sequence,
simplifying handling and minimizing errors, especially with adjacent subsequences.
This logical and efficient approach shapes our language design, emphasizing clarity
@ -3973,6 +3973,11 @@ fn main() {
println(user.name) // "Charles"
user2 := repo.find_user_by_id2(10) or { return }
// To create an Option var directly:
my_optional_int := ?int(none)
my_optional_string := ?string(none)
my_optional_user := ?User(none)
}
```
@ -6224,7 +6229,7 @@ See also [Cross Compilation](#cross-compilation).
## Debugger
To use the native *V debugger*, add the `$dbg` statement to your source, where you
To use the native *V debugger*, add the `$dbg` statement to your source, where you
want the debugger to be invoked.
```v
@ -6234,18 +6239,18 @@ fn main() {
}
```
Running this V code, you will get the debugger REPL break when the execution
Running this V code, you will get the debugger REPL break when the execution
reaches the `$dbg` statement.
```
$ v run example.v
Break on [main] main in example.v:3
example.v:3 vdbg>
example.v:3 vdbg>
```
At this point, execution is halted, and the debugger is now available.
To see the available commands, type
To see the available commands, type
?, h or help. (Completion for commands works - Non-Windows only)
```
@ -6311,7 +6316,7 @@ example.v:3 vdbg> l
0005 }
```
The default is read 3 lines before and 3 lines after, but you can
The default is read 3 lines before and 3 lines after, but you can
pass a parameter to the command to read more lines, like `l 5`.
Now, lets watch the variable changing on this loop.
@ -6331,21 +6336,21 @@ i = 1 (int)
`i` and it's value is automatically printed, because it is in the watch list.
To repeat the last command issued, in this case the `c` command,
To repeat the last command issued, in this case the `c` command,
just hit the *enter* key.
```
example.v:3 vdbg>
example.v:3 vdbg>
Break on [main] main in example.v:3
i = 2 (int)
example.v:3 vdbg>
example.v:3 vdbg>
Break on [main] main in example.v:3
i = 3 (int)
example.v:3 vdbg>
```
You can also see memory usage with `mem` or `memory` command, and
check if the current context is an anon function (`anon?`), a method (`method?`)
check if the current context is an anon function (`anon?`), a method (`method?`)
or a generic method (`generic?`) and clear the terminal window (`clear`).
## Call stack
@ -6387,7 +6392,7 @@ example.v:5 | > main.test
## Trace
Another feature of `v.debug` is the possibility to add hook functions
Another feature of `v.debug` is the possibility to add hook functions
before and after each function call.
To enable this feature, add the `-d trace` switch when building or running
@ -7714,4 +7719,4 @@ Assignment Operators
+= -= *= /= %=
&= |= ^=
>>= <<= >>>=
```
```