Re: [Vala] Why the temporary variables in the C code are usefull ?

Jacques-Pascal Deplaix wrote:
Unwanted side effects can happen if you evaluate an expression more
than once, e.g. if you substituted the full expression for every
_tmp2_ in the C code.  Expressions with side-effects include function
calls and stuff which modifies variables, e.g. p++.  You don't want to
do 'p++' twice or call the function twice.

Thanks.  I give a clearer example of what you're saying:

y = x++ + --x;

No, that isn't what I meant.  Someone who knows the Vala compiler well
could probably come up with a better example, but the compiler could
in theory transform this:

  y = x++;
  z = y * y;

into this:

  z = x++ * x++;

But that would be a mistake.  You need to hold that intermediate 'y'
value somewhere to avoid doing x++ twice.  So some temporary variables
are always needed.


 Jim Peters                  (_)/=\~/_(_)                 jim uazu net
                          (_)  /=\  ~/_  (_)
 UazĂș                  (_)    /=\    ~/_    (_)                http://
 in Peru            (_) ____ /=\ ____ ~/_ ____ (_)  

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]