Re: Uninitialized subtype variables

[math.fu-berlin.de!news.netmbx.de!Germany.EU.net!mcsun!sunic!seunet!enea!s ommar@uunet.uu.net (Erland Sommarskog)]

Robert I. Eachus (eachus@Dr_No.mitre.org) writes:
>     One slight addition to Tucker's list.  Another alternative that a
>compiler can take is to choose to initialize the variable instead of
>doing the check.  This turns out to be a pretty "neat" trick when the
>compiler back-end eliminates assignments of unused values.  If the
>initial value is never used (and the compiler can figure it out) the
>extra assignment is eliminated, otherwise the assignment is usually
>cheaper than the check (for scalars).

Sounds indeed palatable, but...

The variable is no more initialized because the compiler assigned
a value to it, and your program may still behave in mysterious
ways. And since you never stumble on a range check you're likely
to be even more confused.

Or even worse, you develop with the compiler initialization, con-
sciounsly or by mistake, everything works fine, until the day you
port to new compiler which never initializes variables and what used
to be a fine working program is now an inferno of unexplainable random
behaviour.
-- 
Erland Sommarskog - ENEA Data, Stockholm - sommar@enea.se
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