This keeps popping up in my posts. Here's an example of printing out fields of a struct with its names:

import std.stdio;

void main()
{
    struct ASIOChannelInfo
    {
        int channel;
        int isInput;
        int isActive;
        int channelGroup;
        int type;
        string name;
    }

    auto info = ASIOChannelInfo(1, 1, 1, 16, 32, "Analog OUT");

    auto fields = __traits(allMembers, typeof(info));
    auto values = info.tupleof;

    foreach (index, value; values)
    {
        writef("\n%-15s %s", fields[index], value);
    }
}

Prints:
channel           1
isInput            1
isActive           1
channelGroup 16
type             32
name            Analog OUT

I think we could a function in Phobos that does this with a single call. Maybe it could also determine the longest field name and calculate the width specifier for the formatted output so it prints out the columns nicely. It should probably also avoid printing functions. Anyone interested in this type of function? I could give it a shot and implement it.

Btw, is there a lockstep implementation that works with tuples?

On 2011-04-24 23:11, Andrej Mitrovic wrote:
> This keeps popping up in my posts. Here's an example of printing out fields of a struct with its names:
>
> import std.stdio;
>
> void main()
> {
>      struct ASIOChannelInfo
>      {
>          int channel;
>          int isInput;
>          int isActive;
>          int channelGroup;
>          int type;
>          string name;
>      }
>
>      auto info = ASIOChannelInfo(1, 1, 1, 16, 32, "Analog OUT");
>
>      auto fields = __traits(allMembers, typeof(info));
>      auto values = info.tupleof;
>
>      foreach (index, value; values)
>      {
>          writef("\n%-15s %s", fields[index], value);
>      }
> }
>
> Prints:
> channel           1
> isInput            1
> isActive           1
> channelGroup 16
> type             32
> name            Analog OUT
>
> I think we could a function in Phobos that does this with a single call. Maybe it could also determine the longest field name and calculate the width specifier for the formatted output so it prints out the columns nicely. It should probably also avoid printing functions. Anyone interested in this type of function? I could give it a shot and implement it.
>
> Btw, is there a lockstep implementation that works with tuples?

I think it's a good idea. If __traits(allMembers) returns both method and field names then you can use Type.tupleof[0].stringof.

-- 
/Jacob Carlborg

Good idea. .tupleof seems to avoid collecting functions which is perfect. Here's a quick implementation:

http://codepad.org/lSDTFd7E

The only issue I have left is that the function that prints the code doesn't really know what the variable was named in the calling code.

As an alternative I could pass "myvar.stringof" and it would print its name before all field names instead of the type name.

Btw, it seems CTFE doesn't work with this syntax:
foreach (index; 0..100)

But it does work with this syntax:
foreach (index, value; values)

On 2011-04-25 18:47, Andrej Mitrovic wrote:
> Good idea. .tupleof seems to avoid collecting functions which is
> perfect. Here's a quick implementation:
>
> http://codepad.org/lSDTFd7E
>
> The only issue I have left is that the function that prints the code
> doesn't really know what the variable was named in the calling code.

I'm not sure I understand but do you want to print "properties" in this case?

> As an alternative I could pass "myvar.stringof" and it would print its
> name before all field names instead of the type name.
>
> Btw, it seems CTFE doesn't work with this syntax:
> foreach (index; 0..100)
>
> But it does work with this syntax:
> foreach (index, value; values)


-- 
/Jacob Carlborg

On 4/25/11, Jacob Carlborg <doob@me.com> wrote:
> I'm not sure I understand but do you want to print "properties" in this case?

Yeah.