Provoking Some Errors
Our application expects two required configuration values: field.width and field.height. Both must be present, and both must be integers.
In this section, we’ll intentionally introduce a few mistakes into the configuration file to see how errors are reported and handled by the parser.
Missing Values
Let’s begin by commenting out one of the required values in configuration.elcl:
[field]
width: 30
# height: 16
Now run the application again:
$ ./cmake-build/robot-escape/robot-escape configuration.elcl
ValueNotFound: A required value was not found. name path = field.height
Because we’re printing the error message using toText(), the format looks like this:
<Error Class>: <Error Message> <Detail 1> <Detail 2> ...
This format provides both a high-level summary and detailed context, helping you quickly identify the problem.
Wrong Type
Next, let’s see what happens when a value has the wrong type:
[field]
width: 30
height: "text"
Run the application:
$ ./cmake-build/robot-escape/robot-escape configuration.elcl
TypeMismatch: A value has not the required type. Expected Integer but got Text. name path = field.height
This error tells you that the application expected an integer, but received a string instead.
Syntax Error
Finally, let’s introduce a syntax error. In the ELCL format, both section headers and value declarations must start at the beginning of a line. Any indentation will result in a syntax error:
[field]
width: 30
height: 16
Running the app again:
$ ./cmake-build/robot-escape/robot-escape configuration.elcl
Syntax: Value names must appear at the beginning of a line without leading spaces.
at location = (...)/configuration.elcl:3:5
The error message clearly explains the issue and also includes the file name, line number, and column where the error occurred. This makes tracking down problems fast and straightforward.
Recap
As you’ve seen, even in this early stage, the ELCL parser library takes care of the heavy lifting—handling validation, error reporting, and parsing details for you. This allows you to focus more on your application logic and less on boilerplate or edge-case handling.