Hi everyone,

is it possible to program kind of a general function that applies the name of a function (given as a char [] ) to arguments. The following code does not work but something in the same spirit.

Thanks once more to this very patient group.
Oliver

-------

import std.stdio;

int f1( int a ) {
    return a+1;
}

int f2( int b ) {
    return b-10;
}

int apply(char [] name, int arg) {
    return name(arg);
}

int main() {
    int i = 1;
    i = f1(i);
    writefln("i: ",i);
    i = f2(i);
    writefln("i: ",i);
    i = apply( "f1", i );
    i = apply( "f2", i );
    writefln("i: ",i);
    return 0;
}

"oliver" wrote
>
> Hi everyone,
>
> is it possible to program kind of a general function that applies the name of a function (given as a char [] ) to arguments. The following code does not work but something in the same spirit.

As far as I know, this is not possible.  D does not currently support runtime reflection, which is required by this type of function.  Only compile-time reflection is possible.

-Steve

Steven Schveighoffer wrote:
> "oliver" wrote
>> Hi everyone,
>>
>> is it possible to program kind of a general function that applies the name of a function (given as a char [] ) to arguments. The following code does not work but something in the same spirit.
> 
> As far as I know, this is not possible.  D does not currently support runtime reflection, which is required by this type of function.  Only compile-time reflection is possible.
> 
> -Steve 
> 
> 

Flectioned can do it:

http://flectioned.kuehne.cn/

of course, it's a hack/workaround rather than a language feature, but it works (on Win32 it only works if you compile with debug info).

Robert Fraser:
> Flectioned can do it:
> http://flectioned.kuehne.cn/

I know noting still about Flectioned, but maybe it can be used to create something similar to the Python doctest (you may not like it, but some people love it)...
http://docs.python.org/lib/module-doctest.html

bearophile

Thanks to everyone for looking into this. Here is how i have done it now. Oliver

-------------------------------

import std.stdio;

int f1( int a ) {
    return a+1;
}

int f2( int b ) {
    return b-10;
}

void insertInTable( char [] name, int function(int) address, inout int function(int) [ char[] ] table) {
    table[ name ] = address;
}

int function(int) readFromTable( char [] name, int function(int) [ char [] ] table ) {
    if( name in table )
        return table[ name ];

    writefln("Name: ", name ," is not in table.");
    //fix: some default.
}

int main() {
    int function(int) [ char [] ] funcAddressTable;
    insertInTable("f1", &f1, funcAddressTable);
    insertInTable("f2", &f2, funcAddressTable);

    int i = 1;
    i = f1(i);
    writefln("i: ", i);
    i = f2(i);
    writefln("i: ", i);

    auto myF = readFromTable("f2", funcAddressTable);
    i = myF(i);
    writefln("i: ", i);

    return 0;
}

oliver Wrote:

> void insertInTable( char [] name, int function(int) address, inout int function(int) [ char[] ] table) {
>     table[ name ] = address;
> }
[..]
>     insertInTable("f1", &f1, funcAddressTable);
>     insertInTable("f2", &f2, funcAddressTable);
As a side note.
You can also write:
void insertInTable(inout int function(int) [ char[] ] table, char [] name, int function(int) address) {
     table[ name ] = address;
}
insertInTable("f1", &f1);
insertInTable("f2", &f2);

ok, my previous was wrong.

You can also write:
void insert(int function(int) [ char[] ] table, char [] name, int function(int) address) {
     table[ name ] = address;
}

funcAddressTable.insert("f1", &f1);
funcAddressTable.insert("f2", &f2);