Comma operator = broken design

[Adam Ruppe]

Alex Rønne Petersen Wrote:
> I really do not see the value in allowing such syntax in the first 
> place. I've been told that one argument was that generated code might 
> use it, but I have no idea why it would be needed.


Aside from the compiler's implementation, one possible use
is something I ended up doing in Javascript recently.

I have a thing that takes an attribute and pastes it into a code
string to check it.

given validate="this.value.length > 3"

it writes:

if(!(this.value.length > 3))
   return false; // failed validation

since the given string is inside an if statement, you can't put
a semicolon in there.


So, if you have a check more complex than returning a boolean
and want to stuff it all in that string (so functions are out), the
comma lets you do it:

validate="do something, true"



This is pretty ugly style that I think I've only ever done in D inside
a for loop... but the point is sometimes something comes up, and
it's nice to have another option available, even if it is ugly.