std.array : appender woes

[Steven Schveighoffer via Digitalmars-d-learn]

On 6/16/16 6:08 AM, abad wrote:
> On Thursday, 16 June 2016 at 07:59:50 UTC, cym13 wrote:
>> On Thursday, 16 June 2016 at 07:47:03 UTC, abad wrote:
>>> import std.array : appender;
>>> import std.stdio : writeln;
>>>
>>> void main() {
>>>     auto app = appender!(char[]);
>>>     app.put('x');
>>>     auto foo = app.data;
>>>     app.clear; // done, start a new array
>>>     app.put('y');
>>>     writeln(foo);
>>> }
>>>
>>> This prints out 'y'. It's not surprising because what I suppose
>>> app.data is doing is just returning a slice of the dynamic array.
>>> Clear() resets the counter of current position. But this behavior is
>>> confusing in practical use, IMHO.
>>>
>>> Should calling clear in your opinion guarantee that a new array gets
>>> allocated?
>>
>> I don't find it confusing at all, what did you expect?
>
> Consider the word clear in this context. What is it that gets cleared?
> The data in the array (which might imply reallocation)? Nope, what gets
> "cleared" is the index to current position in the array. I think 'reset'
> may have been a better name for the function.

In fact, what gets cleared is the data in the array. You have a dangling 
reference to the array, for which the data is not technically valid.

-Steve