No property 'clear/shrinkTo' for type 'Appender!(string)'

[Steven Schveighoffer]

On Thu, 11 Nov 2010 15:33:41 -0500, Eric Desbiens <olace.mail at gmail.com>  
wrote:

> Hello,
>
> If I create an appender for a string, I cannot call the funtion clear or
> shrinkTo. For example:
>
>     auto strAppender = appender!string();
>     strAppender.clear();
>     strAppender.shrinkTo();
>
> gives compilation error. In std.array source code, it seems that it  
> allows
> those function to work only on types that are not immutable. But on a  
> normal
> string, I can change the length with no problem or reinitialize it.
>
> I am pretty new to D and I just want to be sure that this is a bug before
> reporting it in bugzilla or if this is by design.

It's not a bug, it's to prevent immutable data from being mutated.

When you shrink the length of a builtin string, it does work, but any  
appending from that point will create a copy of that string to append to.   
Appender is built for appending and so is more focused on appending  
in-place.  Therefore, clear and shrinkTo allow you to overwrite the data  
that had already been valid.  This is no good with immutable data.

As a solution, you can simply create a new appender:

strAppender = strAppender.init;

However, that seems limited, now that I look at it.  It may be better to  
allow clear at least to simply reset the appended-to array to null, and  
allow you to start appending again.

Go ahead and file a bug, and mark it as an enhancement.

-Steve