Operator overloading

[Ary Borenszweig]

dennis luehring escribió:
>> It is possible and it works :-)
>> But with operator overloading it is so much more readable, than 
>> without it.
>>
>> Creating queries at runtime is quite common:
>>
>> age = 20;
>> string query = "Select name, surname FROM persons WHERE age = " + 
>> to!(string)(age);
> 
> that is not object + operator based - your flexibilty here comes from 
> your string and the "runtime" interpretation of the sql semantic in your 
> database ...
> 
> if you need an additional "LIKE" based on an codition you need to 
> rebuild your object/operator concatination in complete:
> 
> if( gui.checkbox == true )
> {
>   SELECT a from b
> }
> else
> {
>   SELECT a from b WHERE c LIKE '% ~ C ~ %'
> }
> 
>> Compile time checking of SQLs will not be enough for any bigger program.
>> How would you insert your data into database? INSERT needs values 
>> which are taken e.g. from GUI and completely unknown at compile-time.
> 
> why is a value that comes from an gui not compile-time?
> not the value is what you need - its the type (when we talk about type 
> safetyness)
> 
> how does vector-array get into Don's Blade strings? and why do i get
> compile-time errors when using the wrong type inside of the string?
> 
> and you can't even speak of type-safetyness when using only strings in 
> your database communication - how can be your results typesafe
> (i don't like string[string] results-set) because the safetiness is 
> programatical
> 
>> BTW. In recent release Boost team added a whole brand new library for 
>> domain specific languages embedded languages called Proto. I think 
>> that it means that there is quite a big need for such features. E.g. 
>> for mocking frameworks which will also profit from extended DSL 
>> sublanguages support in programming languages.
> 
> you should read into the details of using mixins - they are much much 
> more flexible than you think (not just boring strings) - and with the 
> base feature-set of D something like mock wouldn't even exist
> and what the boost guys to is to get around c++ base feature-set to 
> express new thing with c++
> 
> @Ary does syntax coloring and smart auto-completen help while writing
> spirit based parsers? the complete meaning of ( * - \ ... is different 
> to "normal" code

I was thinking about LINQ, specifically. Ok, LINQ is too much (and too 
specific), I wouldn't like something like that in D, but something 
similar...

> 
> btw: don syntaxtree is also an great example of using mixins
> http://www.dsource.org/projects/mathextra/browser/trunk/blade/SyntaxTree.d