Re: {} Questions

Ben Bacarisse <ben@bsb.me.uk> wrote:

porkchop@invalid.foo (Mike Sanders) writes:
 

Assuming any awk variant...
>
1. Is this valid? (it works with mawk, gawk, busy box awk)
>
   BEGIN { debug = 1 }
>
   (debug)  { code_here }
>
   (!debug) { code_here }
>
   END { ... }

 
Yes, that's valid.  You don't need the ()s round the expressions.

Thanks Ben.

2. what is the name or accepted term in AWK for unamed functions,
main()?

 
I don't know what you mean.  Can you give an example?
 
It occurs to me that maybe you think
 
  (debug) { code }
 
is a function?  It's not.  It's just a normal pattern/action AWK pair.
An AWK pattern can just be an expression.  That expression is evaluated
for every input line and, if true, the corresponding action is executed.

And yet there's still more implied nuance somehow. Let me try to articulate
my thoughts...

- These types of constructs are 'auto' ran per line of input (assuming
  its not located within another user-written function) that I get.
  Perhaps a potential efficiency hit to be aware of.

- There's also the scope of variables to consider... Because any
  variable's located outside of a user-written function or conversely
  located within a 'bare naked' construct is global, or at least
  exposed to the entire script's 'world', so I want be careful here...

  I'm guessing that any construct that lacks a function signature
  is globally scoped:

  { im_global = 42 }

  while those with a function signature (located within parentheses)
  are locally scoped:

  function private(private_var1) { private_var1 = "foo" }

- And 2 more...

  $ awk '{ v="im_global" }'

  $ awk -f foo -v global=55

  Anything within the above 2 are global as well?

Just thinking aloud here so, I'll let you long time posters describe
it more lucidly.

--
:wq
Mike Sanders