nftables: added support for per-file variable scopes and global variables

Hello,

this series of patches follows a discussion brought here about adding support 
for deeper variable scopes especially in the flat notation. These patches add 
a new variable scope to each include statement. The new scope is a child of 
the parent scope (script in which the include resides). All variables in the 
parent are still accessible in the child but the parent cannot access child 
variables. This effectively creates a tree hierarchy and with the support of 
redefine, one can even mask inherited variables in the child scopes. Sibling 
scopes are not accessible from each other.

If one wants to have some global definitions in a separate script and not 
pollute the top-level script, one can use a new keyword global in the define 
like:

define global global_var=eth0

This puts $global_var to the top-level scope which is accessible from 
everywhere and it survives any include. Global re-definitions and undefines 
are also supported.

On Mon, Apr 30, 2018 at 10:28:16AM +0200, David Fabian wrote:
> Hello,
> 
> this series of patches follows a discussion brought here about adding support 
> for deeper variable scopes especially in the flat notation. These patches add 
> a new variable scope to each include statement. The new scope is a child of 
> the parent scope (script in which the include resides). All variables in the 
> parent are still accessible in the child but the parent cannot access child 
> variables. This effectively creates a tree hierarchy and with the support of 
> redefine, one can even mask inherited variables in the child scopes. Sibling 
> scopes are not accessible from each other.
> 
> If one wants to have some global definitions in a separate script and not 
> pollute the top-level script, one can use a new keyword global in the define 
> like:
> 
> define global global_var=eth0

Better probably "global define" instead, so we make sure no script
using the $global variable outthere breaks.

> This puts $global_var to the top-level scope which is accessible from 
> everywhere and it survives any include. Global re-definitions and undefines 
> are also supported.

Please send us patch using git send-email. Instead of them all
attached to one single email, so patchwork [1] tracks them.

Make sure your patches apply to nftables.git HEAD. Thanks!

[1] http://patchwork.ozlabs.org/project/netfilter-devel/list/
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Dne středa 23. května 2018 9:59:56 CEST, Pablo Neira Ayuso napsal(a):
> On Mon, Apr 30, 2018 at 10:28:16AM +0200, David Fabian wrote:
> > Hello,
> > 
> > this series of patches follows a discussion brought here about adding
> > support for deeper variable scopes especially in the flat notation. These
> > patches add a new variable scope to each include statement. The new scope
> > is a child of the parent scope (script in which the include resides). All
> > variables in the parent are still accessible in the child but the parent
> > cannot access child variables. This effectively creates a tree hierarchy
> > and with the support of redefine, one can even mask inherited variables
> > in the child scopes. Sibling scopes are not accessible from each other.
> > 
> > If one wants to have some global definitions in a separate script and not
> > pollute the top-level script, one can use a new keyword global in the
> > define like:
> > 
> > define global global_var=eth0
> 
> Better probably "global define" instead, so we make sure no script
> using the $global variable outthere breaks.

OK, makes sense. 

> 
> > This puts $global_var to the top-level scope which is accessible from
> > everywhere and it survives any include. Global re-definitions and
> > undefines
> > are also supported.
> 
> Please send us patch using git send-email. Instead of them all
> attached to one single email, so patchwork [1] tracks them.

I managed to send the patch set via git send-email just a moment ago.

> 
> Make sure your patches apply to nftables.git HEAD. Thanks!
> 
> [1] http://patchwork.ozlabs.org/project/netfilter-devel/list/

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