resizeable arrays: T[new]

[Sean Kelly]

Walter Bright wrote:
> Sean Kelly wrote:
>> Given the above, am I correct in assuming that it will only be illegal 
>> to resize an array via .length if the underlying data is const?  If 
>> the data is not const then it seems completely legitimate to resize 
>> the supplied array, even if doing so means an in-place expansion.
> 
> Making the referred to data const does not inhibit resizing, because 
> resizing does not change the referred to data.
> 
> The key to understanding dynamic arrays is understanding their 
> representation. Dynamic arrays of const data are like a C++ struct 
> defined as:
> 
> struct DynamicArray
> {
>     size_t length;
>     const char *ptr;
> }
> 
> Here, I can change .length and .ptr EVEN THOUGH the data being pointed 
> to is const.

Okay, that makes sense.  So I'm not sure I entirely understand the 
problem with resizing even mutable array in place.  Could this just be 
an instance where documentation is indeed sufficient?  I can't think of 
a situation where I would actually pass a slice of a buffer to a routine 
that may grow that buffer when writing to it--it just doesn't make any 
sense from a use perspective.  Is this something that we really need to 
add const features to check?


Sean