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@@ -88,6 +88,38 @@ Run doxygen in the top-level directory and then see build/doc/html/index.html. There are some examples in the examples/ directory. +# Approach to non-compliant DCPs + +In a number of places we read metadata from DCPs that may not be in the correct format. A vague design principle is that we should be +able to read such values, write them back out again the same, and find out that they are invalid. However, it should be difficult to +create new DCPs with badly-formatted metadata. + +For example, a `CPL` has a `MainSoundConfiguration` that is essentially a specially-formatted string: a comma-separated list of values, +where the values come from a limited range. A correct value might be "L,R,C,LFE,Ls,Rs,-,-" and an incorrect one "fish" or +"01,02,03,04,05,06" + +The "happy" path is: + +``` +MainSoundConfiguration foo("L,R,C,LFE,Ls,Rs,-,-"); +std::cout << "Config has " << foo.channels() << ", first is mapped to " << dcp::channel_to_mca_name(foo.mapping(0).get(), foo.field()) << "\n"; +std::cout << "Value for XML: " << foo.to_string() << "\n"; +``` + +In this case `foo.valid()` will be true and the details of the configuration can be accessed. + +In the "invalid" case we have: + +``` +MainSoundConfiguration foo("01,02,03,04,05,06"); +std::cout << "Value for XML: " << foo.to_string() << "\n"; +``` + +Now `foo.valid()` will be `false` and calls to (for example) `foo.channels()` will throw `MainSoundConfigurationError`. `foo.to_string()` is +OK, however, and will return the same invalid string "01,02,03,04,05,06" as was passed to the constructor. + + + # Coding style * Use C++11 but nothing higher, as we need the library to be usable on some quite old compilers. |