[BUG] .append() member procedure doesn't work if vector created implicitly

[jembrown]

Describe the bug
When a vector is created implicitly by assigning a value to its first position, the .append() member procedure doesn't work. However, it does work if the vector is created using v().

To Reproduce

# Case 1
> z[1] <- 1
> z
   [ 1 ]
> z.append(2)
> z
   [ 1 ]

# Case 2
> z <- v(1)
> z
   [ 1 ]
> z.append(2)
> z
   [ 1, 2 ]

Expected behavior
All member procedures should be available to all vectors, regardless of how they are created.

[hoehna]

The issue is that in the first case there doesn't actually exist the vector in memory, only the elements of the vector z[1]. When you call 'z' it creates a temporary vector, so you append to the temporary vector that then gets thrown away.

I see that this is confusing but I'm not super sure how easy that is to fix.

[jembrown]

Ah, ok. I didn't realize that's how vectors were handled in the first case. Perhaps that's ok if (i) the .append() method doesn't appear when you call z.methods() and/or (ii) an error is displayed when trying to call .append() on a temporary vector?