Converting a list of words or array of values to variables at compile time

[drug via Digitalmars-d-learn]

On 26.11.2015 09:33, Louie F wrote:
> I found out that compile time optimization is quite useful specially for
> database queries, instead of it being generated at every call, it can be
> generated like I typed it using compile time optimizations... so I thought,
>
> Is it possible to convert an array of values or a list from a file to
> variables or struct at compile time?
>
> So basically I have a database, instead of writing a struct, I would
> like to query the database for the list of tables and their column
> information then parse that as a struct or variables for parsing so that
> I could use it, so that if I delete or add columns I then only need to
> recompile the code and not worry about editing files...
>
> class Users
> {
>        /*
>              query the database and create fields at compile time and
> use the variables below
>        */
>
>        void create(){
>              this.name = "Louie";
>         }
>
> }
>
> or  something like this...
>
> foreach(table_names, key; table){
>          /*
>                generate struct using table and informations
>         */
> }
>
>
>
you can do something like:

auto createColumnDescription(Description...)()
{
     string s;
     foreach(description; Description){
         s ~= description[0] ~ " " ~ description[1] ~ ";\n");
     return s;
}

struct Table(ColumnDescription)
{
     // pragma(msg, createColumn!ColumnDescription);  // uncomment this 
to see what will be mixed
     mixin(createColumn!ColumnDescription);
}

the table contains a range of tuples of column type and name and should 
be available at compile-time

But it isn't tested and I'm not sure it's the best way.