Well, we already have in-image a #once like solution based on memoization. block := [ :key | key factorial ] memoized.
"first time" [1000 to: 1500 do: [:index |block value: index]] timeToRun. "0:00:00:01.598" "second time, cached" [1000 to: 1500 do: [:index |block value: index]] timeToRun. "0:00:00:00" And it requires no compiler nor syntax changes. In any case, changing the compiler would be good as: - an example of how to write opal extensions - an additional package for those who would like to play and do hacky stuff (why not huh?) So I would not discourage it (but it would be good to have it as an extra loadable package instead of an in-image one). Guille El lun., 15 de jun. de 2015 a la(s) 10:08 a. m., Ben Coman < b...@openinworld.com> escribió: > whoops. please excuse my previous clicktoofast. > > On Mon, Jun 15, 2015 at 3:51 PM, Clément Bera <bera.clem...@gmail.com> > wrote: > > Hey all, > > > > Holger Freyther, I didn't know about ##() and once in GNU Smalltalk, but > > that was definitely what I was trying to experiment with. > > > > As Thierry mentioned, these elements come from C/C++ where you have > macros > > that are very useful when writing high performance code so your code can > be > > both flexible and very efficient. > > > > Ben you're right, normal users should not be confused by those features > or > > new syntax elements. For CValue, I added class-side of the classes using > it: > > > > MyClass>>#compiler > > | comp | > > comp := super compiler. > > comp compilationContext semanticAnalyzerClass: NeoCompiler. > > ^ comp > > > > I think the solution for this problem is to do another Opal compilation > > options for precompilation. This way, if you want to use your compiler > > extension, you have either to: > > - override #compiler class side for a hierachy of classes granularity > > - add a pragma such as <compilationOptions: + optionPrecompilation> for a > > per method granularity > > To make it more explicit, possibly consider requiring the special > selector to be mentioned in the pragma. > <precompile: #once> or <precompile: #Cvalue> > > Now I wonder how this precompiled code might look or operate within a > debugger? > cheers -ben > > > > > > then in the methods affected by the compiler extension, you can either > use a > > different parser with new syntax elements such as ##() or use new special > > selectors such as #once or #Cvalue. > > > > > > 2015-06-15 7:13 GMT+02:00 Thierry Goubier <thierry.goub...@gmail.com>: > >> > >> Hi Ben, > >> > >> > >> Le 15/06/2015 01:09, Ben Coman a écrit : > >>> > >>> On Mon, Jun 15, 2015 at 2:34 AM, Thierry Goubier > >>> <thierry.goub...@gmail.com> wrote: > >>>> > >>>> Le 14/06/2015 18:39, Holger Freyther a écrit : > >>>>> > >>>>> > >>>>> > >>>>>> On 13 Jun 2015, at 14:39, Clément Bera <bera.clem...@gmail.com> > wrote: > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> Dear Clement, > >>>>> > >>>>>> This is an interesting problem. There is currently no simple way of > >>>>>> executing a message at compile-time instead of at runtime in Pharo, > >>>>>> which is > >>>>>> useful to have settings but no runtime overhead. > >>>>>> > >>>>>> I did a simple extension for opal compiler for this purpose, adding > >>>>>> the > >>>>>> message Cvalue, which is compiled by Opal either to its receiver's > >>>>>> block > >>>>>> value or the result of its value depending on the result of > >>>>>> #allowPrecompilation sent to its class using AST manipulation before > >>>>>> the > >>>>>> semantic analysis. > >>>>> > >>>>> > >>>>> > >>>>> are you aware of the compile time constants in GNU Smalltalk. The > >>>>> syntax > >>>>> that was > >>>>> picked is ##(EXPR). E.g. the below is an example for usage in GNU > >>>>> Smalltalk. > >>>>> > >>>>> > >>>>> someMethod > >>>>> ^##(Character value: 8) > >>>>> > >>>>> the compiler will create a CompiledMethod that holds a literal ($<8>) > >>>>> and > >>>>> will return > >>>>> it. In general I find that syntax quite nice. > >>>> > >>>> > >>>> > >>>> When porting SmaCC from the Dolphin version, I found that optimisation > >>>> in > >>>> many places, as well as methods returning once blocks: > >>>> ^ [ Dictionary new add: .... ] once. > >>>> > >>>> So, I'd say that Cvalue is the same as once :) > >>>> > >>> > >>> Does #once evaluate at compile time? > >>> Or the first pass at run-time? > >>> The latter would have a different runtime overhead to CValue. > >> > >> > >> I don't know. It could even be at first run with a recompilation of the > >> method, to add another solution to the mix :) > >> > >>> There are probably valid arguments for not introducing new syntax > >>> (including cross-dialect compatibility), but for something that occurs > >>> at compile-time rather than run-time, I think I'd prefer syntax to a > >>> keyword. To reuse existing elements that are not compiled, that is > >>> either comment quotes or pragma angle brackets. Maybe combine pragma > >>> with an executable block... > >>> <[ doThis at compileTime ]> > >> > >> > >> #define and friends it is :) In short, a dedicated syntax for compile > >> time... aka macros. > >> > >> Thierry > >> > >> > > > >
