Intro | Part 1 | Part 2 | Part 3

Exercises in error handlingExercises in error handling

The error messages are more confusing than helpful. They are intended as help, but are somewhat cryptic, sorry. Here are the most common messages. Errors show up when there is no output available.

Similar in the real world, things only work when they get the correct input, for instance a TV requires a power cable and an antenna cable to work. If its a bad antenna signal then it wont work and you may get an error message. If there is a power problem, then you will not see any error messages.

Also see this video at youtube.

1st step

Too few inputsToo few inputs
 

Create the same construction as in the left side of the figure. The 'Pad' brick shows this message: 

ERROR: Too few inputs. Expected 1 inputs, but got 0.
ERROR: Could not resolve buffer-type.

In the right side of the figure there are no message. The 'Pad' brick and the 'Text' brick are connected.
 

What about 'too many inputs'?
 

Extra inputs are ignored. A brick such as 'Pad' that requires 1 input. When passing it 2 inputs then the left most input will be used and the right most input will be ignored.

2nd step

Expected needed inputs to be settledExpected needed inputs to be settled

Create the same construction as in the left side of the figure. The 'Mix' brick shows this message:

ERROR: Expected needed inputs to be settled, but input#0 is NULL!
ERROR: Could not resolve buffer-type.

In the right side of the figure there is no message. By connecting the 'Pad' brick and the 'Text' brick the message went away.
 

What are 'nested errors'?
 

What happens in the figure is called a 'nested error'. The 'Mix' brick only works when its inputs works, it gets garbage input. The actual problem is within 'Pad' and its the same as in 1st step.

3rd step

Expected GraphicsBufferTypeExpected GraphicsBufferType

Create the same construction as in the left side of the figure. The 'Crop' brick shows this message:

ERROR: Expected GraphicsBufferType on input#0, but got MeshBufferType!
ERROR: Could not resolve buffer-type.

This is more difficult to fix.
 

What are 'type errors'?
 

A real world example are the electrical plugs and sockets, they differ by country in shape, size and type of connector. It causes problems for travelers that must use adaptors. These problems are 'type errors'.

SummarySummary

As you can see there is room for improvement. The error messages are bad. Keep in mind "Garbage in, garbage out".

This is the last part of the tutorials.