Programming Python, 3rd Edition

Utility Modules

This section presents the source code of the utility modules imported and used by the page scripts shown earlier. As installed, all of these modules live in the same directory as the CGI scripts, to make imports simple—they are found in the current working directory. There aren’t any new screenshots to see here because these are utilities, not CGI scripts. Moreover, these modules aren’t all that useful to study in isolation and are included here primarily to be referenced as you go through the CGI scripts’ code. See earlier in this chapter for additional details not repeated here.

External Components and Configuration

When running PyMailCGI out of its own directory in the book examples distribution tree, it relies on a number of external modules that are potentially located elsewhere. Because all of these are accessible from the PP3E package root, they can be imported with dotted-path names as usual, relative to the root. In case this setup ever changes, though, the module in Example 17-10 encapsulates the location of all external dependencies; if they ever move, this is the only file that must be changed.

Example 17-10. PP3E\Internet\Web\PyMailCgi\externs.py

############################################################################# # Isolate all imports of modules that live outside of the PyMailCgi # directory, so that their location must only be changed here if moved; # we use a custom version of mailconfig.py here: a pymailgui2 subset ############################################################################# ...