Please help me understand this function signature: std.stdio.File.byLine

[Tejas]

On Thursday, 15 July 2021 at 18:08:45 UTC, Scotpip wrote:
> Hi folks
>
> Settling down to write my first app but have come to a grinding 
> halt. This is my first system-level language so I'm afraid I'll 
> be asking some naïve questions.
>
> All I'm trying to do is read a text file with Windows line 
> endings into an array for line-by-line processing.
>
> The relevant function appears to be 
> [std.stdio.File.byLine](https://dlang.org/library/std/stdio/file.by_line.html).
>
> The default isn't breaking the lines properly, so I have to 
> pass in the line ending. But the signature has me baffled:
>
> ```
> auto byLine(Terminator, Char) (
>   KeepTerminator keepTerminator = No.keepTerminator,
>   Terminator terminator = '\x0a'
> )
> if (isScalarType!Terminator);
>
> auto byLine(Terminator, Char) (
>   KeepTerminator keepTerminator,
>   Terminator terminator
> )
> if (is(immutable(ElementEncodingType!Terminator) == 
> immutable(Char)));
> ```
>
> To specify the line ending, it appears to be asking for a type 
> "Terminator" which I can't find in the library. Doing the 
> obvious doesn't work:
>
> ```
> // Err: cannot deduce function from argument types
> myFile.byLine(`\r\n`);
> ```
> Also, how would you specify the Char type as a parameter?
>
>
> The examples are unenlightening as they only show the default 
> case, so any help would be much appreciated. Any wider tips on 
> how to read these cryptic signatures would be a bonus!

Sorry I'm on mobile right now so can't help much, but if you're a 
beginner, please read the book "programming in D" by Ali Cehreli.


http://ddili.org/ders/d.en/

If you just want to learn about files for now, visit this link, 
it contains a chapter of his book(regrettably it doesn't cover 
your exact usecase but maybe ```readln``` might work out for you)

http://ddili.org/ders/d.en/files.html