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From: Janis Papanagnou <janis_papanagnou+ng@hotmail.com>
Newsgroups: comp.lang.awk
Subject: Re: {} Questions
Date: Wed, 21 Aug 2024 14:08:08 +0200
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On 21.08.2024 13:48, Mike Sanders wrote:
> 

[ Concerning the basic awk syntax:  condition { action }  ]

> 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.

You cannot have these constructs with their given semantics inside a
function. You'd have to formulate them explicitly (in the imperative
form) with 'if', as in

  function f ()
  {
      if (condition) action
  }

>   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...

All variables have global scope, with the exception of those specified
in a function argument list along with the real arguments, as in

  function f (arg1, arg2,   local1, local2)  { global = arg1 ; ... }
  f ("Hello", 42);

(There's some caveat with arrays in the function argument list.)

Janis

> 
>   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.
>