NFD » ndn-cxx

I had impression that TPM location (for file-based TPM) is relative to PIB, unless specified explicitly. If I'm wrong, we may need to actually implement this guarantee.

may I suggest NDN_PIB_DIR as the name of the env variable?

Location of client.conf doesn't need to be (and for test cases, it should not, otherwise they will break) tied to location of PIB/TPM. We may introduce different variable than TEST_HOME, but I would like not to tangle them together.

An alternate is to specify the location of client.conf in NDN_CLIENT_CONF_PATH.

An advantage over NDN_PIB_DIR is that it allows all configuration options to be customized through the use of the environ combined with something on the filesystem.

Note that NDN_PIB_DIR still relies on the filesystem for storing PIB+TPM, and there isn't much benefit in not writing a client.conf.

NDN_PIB_DIR can cause confusion when NDN_PIB_DIR environ and PIB/TPM locator in effective client.conf points to different locations, or when client.conf specifies a PIB/TPM that is not file-based.

Imagine there's a MySQL-based PIB.
You can select that with NDN_CLIENT_CONF_PATH but not NDN_PIB_DIR.

What about another option: three variables corresponding to the config file.

• NDN_TRANSPORT (or NDN_CLIENT_TRANSPORT): equivalent of transport in client.conf
• NDN_PIB (or NDN_CLIENT_PIB): equivalent of pib in client.conf
• NDN_TPM (or NDN_CLIENT_TPM): equivalent of tpm in client.conf

There is a little bit of a hassle of just specifying location of the client.conf, as one needs to create that file.

note-11 solution is as good as NDN_CLIENT_CONF_PATH.

I prefer the environ names with _CLIENT_ component.

More design questions:

Should Face default constructor throw an error if NDN_CLIENT_TRANSPORT is valid but the transport key in configuration file is invalid?

Should Face constructor that takes an explicit Transport instance throw an error if NDN_CLIENT_TRANSPORT or transport key in configuration file is invalid?

If config is overridden by the environment, the config file should be inactive. If env correct, no exceptions should be thrown.

note-15 only answers the first question in note-14. The second question remains.

I think you are asking questions with obvious answers. If Transport is explicitly specified (unless it is nullptr), config file is not opened, so no error can be triggered.