Re: [TCLCORE] Fwd: TIP 672 Implementation Complete - Ready for Sponsorship

[Pietro C. <ga...@ga...>]

How does it handle a space between a mathfunc and its parenthesized argument list?

% expr {sin (12)}
-0.5365729180004349

-- 
Pietro Cerutti
I've pledged to give 10% of income to effective charities and invite you to join me.
https://givingwhatwecan.org

Sent from a small device - please excuse brevity and typos.


> On 1 Nov 2025, at 17:50, Colin Macleod via Tcl-Core <tcl...@li...> wrote:
> 
> 
> On 30/10/2025 01:18, Andreas Leitgeb wrote:
>> 
>>    - [= ...] with a modified expr-language using barewords as variable
>>     names would probably solve many (if not most) of the cases, where
>>     [expr {...}] really "hurts" for its verbosity.
> Here is a pure Tcl implementation of that:
> 
> proc = args {
>     set ex [join $args]
>     set exp [regsub -all {(::)?[[:alpha:]]([[:alnum:]_]|::)*([^[:alnum:]_(]|$)} $ex {$&}]
>     uplevel expr $exp
> }
> 
> This just finds all the possible variable names in the expression, prefixes them with $ and then runs expr on the result.  The regex is a little complicated because:
> 
> The variable name could include :: at the beginning or in the middle for namespacing.
> We disallow single colon : within the name because that creates ambiguity with the ternary operator ?: .
> We also disallow array references because we can't distinguish them from mathfunc calls.
> The fact that this can be implemented in pure Tcl shows that it doesn't require any change to the dodekalogue rules, and so there is no consequence for subst either.
> 
> Of course a real implementation should be done in C.  It could then also be possible to implement the extension Kevin Kenny suggested of adding `=` as an assignment operator as in C within an expression, and perhaps even chaining multiple assignments with `,` .
> 
> I saw the `expr` question is on the agenda for the call on Monday.  I don't usually join these calls but I would join it for this issue except that I have an urgent dentist's appointment at that time.  Perhaps I should create a new TIP for this proposal?
> 
> Colin.
> 
> _______________________________________________
> Tcl-Core mailing list
> Tcl...@li...
> https://lists.sourceforge.net/lists/listinfo/tcl-core