Ruby and enumeration

[Superp]

Hello,

I have a question about discovery of devices with Ruby. Enumeration supplies the numeric device_identifier for each device, for instance 2103 for a 'LED Strip Bricklet 2.0'.

See documentation.

Next steps would be to load the file defining the matching class, and to initialize an instance of that class:

require 'tinkerforge/bricklet_led_strip_v2'

Tinkerforge::BrickletLEDStripV2.new ...

In other words, I need the name of the matching class for a '2103 device' and the file which defines that class.

Tinkerforge::DEVICE_DISPLAY_NAMES only maps device_identifier to device_display_name.

How do I map numeric device_identifier to class and file?

One way would be to load all 139 device classes, and than loop through all Tinkerforge::Device descendants until I find the one with the matching DEVICE_IDENTIFIER constant. That sounds like a really bad idea.

Has anyone figured this out yet?

bearbeitet December 1, 2020 at 10:55 von Superp
a %#@& typo

[photron]

Tinkerforge::DEVICE_DISPLAY_NAMES is internal for error message purposes.

What you're looking for is a device factory. The Ruby bindings don't have that.

7 hours ago, Superp said:

One way would be to load all 139 device classes, and than loop through all Tinkerforge::Device descendants until I find the one with the matching DEVICE_IDENTIFIER constant. That sounds like a really bad idea.

That's not a bad idea at all, that basically how Brick Viewer solves this problem. But instead of doing a linear search, Brick Viewer builds a dictionary that maps device identifier to device class and then uses that dictionary to do the lookup efficiently.

What are you trying to build that requires a device factory?

[Superp]

Hi Photron,

Thanks for responding. I am basically just a lazy programmer who likes magic.

What I have done so far is write a little bit of Ruby that 1) takes stock of Device descendants. 2) requires one of TF's source-files. 3) takes stock again and compares to (1) to identify any newly defined class. 4) gets DEVICE_IDENTIFIER and DEVICE_DISPLAY_NAME from the newly defined class. 5) Repeats for all source-files.

This generates a device_info.txt which maps device_identifier, device class, source-file, and device_display_name. You can use any of these four to look up the other three.

This is my third week of using TF and I hope to make it part of a fairly big project. 

[Superp]

So, I think I found a working solution, which I'll share here in case anyone else runs into the same limitation.

Tinkerforge.device_info 2103
=> [2103, "LED Strip Bricklet 2.0", ["Tinkerforge::BrickletLEDStripV2", "bricklet_led_strip_v2"]]

and

my_devices = Tinkerforge.connect.discover

Source here.