4.3 Packages

Packages in plasT_eX are loaded in one of three ways: standard L^aT_eX package, Python package, and INI file. L^aT_eX packages are loaded in much the same way that L^aT_eX itself loads packages. The kpsewhich program is used to locate the requested file which can be either in the search path of your L^aT_eX distribution or in one of the directories specified in the TEXINPUTS environment variable. plasT_eX read the file and expand the macros therein just as L^aT_eX would do. This happens only if the --load-tex-packages option is set (which is the default value), or the package is white-listed in the --tex-packages option (see Section2.1.1). It will work as expected only for simple packages.

Python packages are located by successively trying three strategies. First plasT_eX looks into the directories listed in the --packages-dirs option (see Section2.1.1), in the order they are listed. If this fail then plasT_eX looks into the plugins listed in the --plugins option (see Sections 2.1.1 and 6.8), in the reversed order they are listed (the general idea here is that later plugins are allowed to overrule earlier ones). If this also fails then plasT_eX looks into the builtin packages folder that comes with every installation of plasT_eX. After a package is loaded, it is checked to see if there is a function called ProcessOptions in its namespace. If there is, that function is called with two arguments: 1) the dictionary of options that were specified when loading the package, and 2) the document object that is currently being processed. This function allows you to make adjustments to the loaded macros based on the options specified, and define new commands in the document’s context (see section 4.2.3 for more information). Of course, you can also define Python based macros (section 4.2.1) in the Python package as well.

The last type of packages is based on the INI file format. This format is discussed in more detail in section 4.2.2. INI formatted packages are loaded in conjunction with a L^aT_eX or Python package. When a package is loaded, an INI file with the same basename is searched for in the same director as the package. If it exists, it is loaded as well. For example, if you had a package called ‘python.sty’ and a file called ‘python.ini’ in the same package directory, ‘python.sty’ would be loaded first, then ‘python.ini’ would be loaded. The same operation applies for Python based packages.