Re: Simultaneous Assignment

2013-12-10 Thread Andrea Fontana 

On Monday, 9 December 2013 at 13:57:04 UTC, qznc wrote:

  int x;
  if((x = some_long_expression.here)  0) {
writefln(x is %s, x);
  }

The bad news is that this means type inference cannot be used 
here (no auto) and the variables is declared in a wider scope 
than just the if-body.


Ok then write:

{
  auto x = some_long_expression.here;
  if (x  0) {
writefln(x is %s, x);
  }
}

Re: Simultaneous Assignment

2013-12-09 Thread qznc 

On Monday, 9 December 2013 at 07:38:04 UTC, Dfr wrote:

Does D has somtething similar ?

http://code.google.com/p/go-wiki/wiki/SimultaneousAssignment


No, not in general. There are a few special cases, though.

The foreach loop can assign value and index simultaneously.

  foreach (int i, char c; a) {
writefln(a[%d] = '%c', i, c);
  }

Many things can be done in the library. For example, the variable 
swap from your link:


  swap(i,j); // more: http://www.dpaste.dzfl.pl/582f7ae2

For returning multiple values from a function in D, you use 
std.typecons.tuple.



I tried this way, but it not worked out.

if((int x = 10)  0) {
writefln(x is %s, x);
}


Could you give more context for your specific example? What are 
you trying to do?

Re: Simultaneous Assignment

2013-12-09 Thread Dfr 


Sorry, it was misnomer in topic title. But simultaneous 
assignment also useful topic to learn.


What i trying to achieve in my current example is more succinct 
code.

A coming from Perl and instead of writing:

if(some_complex_statement.here  0) {
writefln(x is %s, some_long_expression.here);
}

I got used not to repeat complex statement, but use 'x' as quick 
alias:


if((int x = some_complex_statement.here)  0) {
writefln(x is %s, x);
}


On Monday, 9 December 2013 at 08:28:48 UTC, qznc wrote:


Could you give more context for your specific example? What are 
you trying to do?

Re: Simultaneous Assignment

2013-12-09 Thread qznc 

On Monday, 9 December 2013 at 09:32:26 UTC, Dfr wrote:
What i trying to achieve in my current example is more succinct 
code.

A coming from Perl and instead of writing:

if(some_complex_statement.here  0) {
writefln(x is %s, some_long_expression.here);
}

I got used not to repeat complex statement, but use 'x' as 
quick alias:


if((int x = some_complex_statement.here)  0) {
writefln(x is %s, x);
}


Afaik, D has no StatementExpression, which means no declarations 
inside expressions. However, there is an AssignExpression, so 
assignment works, but requires the declaration before.


  int x;
  if((x = some_long_expression.here)  0) {
writefln(x is %s, x);
  }

The bad news is that this means type inference cannot be used 
here (no auto) and the variables is declared in a wider scope 
than just the if-body.

Simultaneous Assignment

2013-12-08 Thread Dfr 

Does D has somtething similar ?

http://code.google.com/p/go-wiki/wiki/SimultaneousAssignment

I tried this way, but it not worked out.

if((int x = 10)  0) {
writefln(x is %s, x);
}