[Oberon] Obstacles when programming in RISC Oberon and proposed patches

[Richard Hable]

On 05/24/14 22:13, Michael Schierl wrote:

> 1. Uninitialized local variables
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> When something is allocated on the heap with NEW, all bytes are zeroed
> out (in Kernel.New). Variables declared at the top of the module are
> also zeroed out (in Modules.Load). Only local variables that live on the
> stack are not zeroed out, but stay what they are. It is easy to miss an
> initialization, resulting in a program that "sometimes works". On the
> other hand, it is also easy to patch the compiler to zero out these
> stack areas:

But this would lead to inefficiency and incompatible Oberon programs 
relying on automatic initialization of local variables.

I would prefer a solution similar to Java, where the compiler does not 
allow reading local variables, if it isn't sure that they have already 
been assigned a value. The Oberon compiler could create warnings in 
such cases.

Richard