why use string for this example of appender?

[Steven Schveighoffer]

On 4/16/18 4:49 AM, Ali Çehreli wrote:
> On 04/15/2018 11:46 PM, WhatMeForget wrote:
>  >
>  > I think I got a handle on D's static and dynamic arrays, till I come to
>  > std.array and see all the shiny new tools. I can understand all the
>  > replace.. functions, but the appender function gave me pause. The
>  > documentation says appender "Returns a new Appender or RefAppender
>  > initialized with a given array."
> 
> New Appender allocates new memory. If an array is already available for 
> an Appender to use, then it's more efficient.
> 
>  > My first thought that doesn't D's built in arrays already allow
>  > appending? (at least for dynamic arrays)
> 
> Yes but Appender is reported to be faster presumably it uses a different 
> allocation scheme and may be more free compared to dynamic arrays that 
> must play well with GC and its pages.

It's because it stores the relevant information in a local type vs. 
having to look it up in the GC.

It's also not all opaque calls (they can be inlined).

>  > Another thing that had me wondering is the use of put()
>  > down below; doesn't the append syntax (~=) give you the same exact
>  > functionality; so why bother?
> 
> put() is old, ~= is new. Both are supported.
> 

put is required for Appender to be an output range.

-Steve