Re: [bug-gawk] gawk 5.0.1 patch to allow *valid* awk variable names to be assigned to SYMTAB

[arnold]

Peter,

I have to agree with Tom here. From the snippet you sent, it doesn't
look like there's a significant advantage to your using SYMTAB.

Arnold

Tom Gray <address@hidden> wrote:

> HI Peter,
>
> Have you considered using your own array instead of SYMTAB[]
> Lets call it mem[] ... to represent some generic storage space.
> Then the index will not have any "nice variable name" restrictions.
>
>       FNR == 1 { for (I = 1; I <= NF; i++) { mem[$i] = computed_value } }
>
>       If ((mem[MyVar] > x) && (mem[MyVar] < y)) { do-something
>
> In my opinion Gawks jagged arrays of arrays are the best thing since sliced 
> bread.
> Combined with recursion and indirect function calls you get incredible power.
>
> Do not underestimate the power of portability.  If you write something cool, 
> you want others to be able to use it.
>
> Tom
>
> -----Original Message-----
> From: bug-gawk <bug-gawk-bounces+tom_gray=address@hidden> On Behalf Of 
> address@hidden
> Sent: Sunday, October 13, 2019 5:25 PM
> To: address@hidden
> Cc: address@hidden
> Subject: Re: [bug-gawk] gawk 5.0.1 patch to allow *valid* awk variable names 
> to be assigned to SYMTAB
>
> [EXTERNAL]
>
> Hi Arnold,
>
> In further testing of my patch to interpret.h, I have found that there is at 
> least one issue no doubt due to my ignorance of the correct structure and 
> linking of Node * structures.
>
> In short, assigning a number of dynamic field names (e.g., field values input 
> from a file using $1, $2, etc.) into SYMTAB seems to leave all of those 
> newly-created variables pointing to the value of the last one entered into 
> SYMTAB.
>
> I have not yet nailed down why that happens, but as I said I suspect it is my 
> ignorance of the proper chaining and adjustment of the Node * structures that 
> is at fault.
>
> Is there any internal developer design documentation on the actual structure 
> of the SYMTAB Node * structures other than the source code itself?  A visual 
> chart of any kind (ASCII art, Visio or any open source equivalent like 
> LibreOffice Draw or Pencil, etc.) would be a great help.
>
> In particular, for the interpret.h operations Op_subscript_lhs and 
> Op_stor_sub, what value is the "lhs" Node * value pointing at after the 
> assignment "lhs = assoc_lookup(t1, t2);"?
>
> I apologize for my ignorance about these internal structural issues.  I am 
> only trying to get to the place where I can safely assign dynamically created 
> variable names and then later use their dynamically assigned values, as in 
> for example:
>
> FNR == 1 { for (I = 1; I <= NF; i++) { SYMTAB[$i] = computed_value } } # 
> Where $i has been previously verified as a valid gawk variable name value, or 
> suitably adjusted to be one
>
> Where for instance $4 == "MyVar", and then later in the program I can use 
> code like:
>
> If ((MyVar > x) && (MyVar < y)) { do-something }
>
> -- or --
>
> MyVar ~ /Some-valid-RE/ { do-something }
>
> I admit that this is a limited use case, but it would be a significant help 
> in my personal projects (not intended for general distribution anywhere).
>
> Peter
>
> P.S. -- If I can gain an acceptable level of understanding of the Node * 
> structures and linking and no current visual representation is available, I 
> would be willing to create such a visual representation for the project to 
> use.
>
> > -----Original Message-----
> > From: address@hidden <address@hidden>
> > Sent: Tuesday, October 8, 2019 9:10 PM
> > To: 'address@hidden' <address@hidden>
> > Cc: 'address@hidden' <address@hidden>
> > Subject: RE: [bug-gawk] gawk 5.0.1 patch to allow *valid* awk variable
> names
> > to be assigned to SYMTAB
> >
> > Hi Arnold,
> >
> > You are welcome.  I do understand about paperwork issues, if needed I 
> > will supply anything required.
> >
> > Let me know when you find the round tuits to look over the patch.  I 
> > know
> all
> > too well how scarce those can be.
> >
> > Regards,
> >
> > Peter
> >
> > > -----Original Message-----
> > > From: address@hidden <address@hidden>
> > > Sent: Tuesday, October 8, 2019 3:25 AM
> > > To: address@hidden
> > > Cc: address@hidden
> > > Subject: Re: [bug-gawk] gawk 5.0.1 patch to allow *valid* awk 
> > > variable names to be assigned to SYMTAB
> > >
> > > Hi.
> > >
> > > Thanks for this. I'll review the patch.
> > >
> > > > I assign any rights I may have in the patch code to GNU.
> > >
> > > Unfortunately, a simple statement such as this in an email just 
> > > doesn't work.  If I decide to use the patch, and that the patch 
> > > needs paperwork (it might be small enough to not require it) then 
> > > you'll have to do a formal assignment of copyright to the FSF.  
> > > (It's their code, I have to play by their rules.)
> > >
> > > This process is relatively painless, although often a bit tedious.
> > >
> > > I am busy for the next while, but I'll eventually give this some 
> > > attention and get back to you.
> > >
> > > In all cases, *thank you* for wanting to contribute.
> > >
> > > Arnold
>
>