• Kagamin <spam here.lot> Mar 26 2011
• "Steven Schveighoffer" <schveiguy yahoo.com> Mar 28 2011

Kagamin <spam here.lot> writes:

Steven Schveighoffer Wrote:

 For example, if I do:
 
 sqrt(1);
 
 There is never ever a need to test this in production code.  sqrt(1) is  
 always 1, and will always work.
 
 If I do:
 
 sqrt(-1);
 


pure function called on literals is evaluatable at compile time together with
checks, so if sqrt run at runtime, this means input couldn't be validated that
easily, so checks should be run too. This means that it's unnecessary to ever
remove checks from sqrt.

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Sat, 26 Mar 2011 08:14:19 -0400, Kagamin <spam here.lot> wrote:

 Steven Schveighoffer Wrote:

 For example, if I do:

 sqrt(1);

 There is never ever a need to test this in production code.  sqrt(1) is
 always 1, and will always work.

 If I do:

 sqrt(-1);


 pure function called on literals is evaluatable at compile time together  
 with checks, so if sqrt run at runtime, this means input couldn't be  
 validated that easily, so checks should be run too. This means that it's  
 unnecessary to ever remove checks from sqrt.


It's not that simple.

for example:

sqrt(uniform(1.0, 2000.0));

This is completely safe, and needs no runtime error checks.

It's easier to explain with simple examples, knowing that you can  
extrapolate more complex ones that the compiler can't "prove".

-Steve