preferences.rst

Preferences

Brian has a system of global preferences that affect how certain objects behave. These can be set either in scripts by using the prefs object or in a file. Each preference looks like codegen.c.compiler, i.e. dotted names.

Accessing and setting preferences

Preferences can be accessed and set either keyword-based or attribute-based. The following are equivalent:

prefs['codegen.c.compiler'] = 'gcc'
prefs.codegen.c.compiler = 'gcc'

Using the attribute-based form can be particulary useful for interactive work, e.g. in ipython, as it offers autocompletion and documentation. In ipython, prefs.codegen.c? would display a docstring with all the preferences available in the codegen.c category.

Preference files

Preferences are stored in a hierarchy of files, with the following order (each step overrides the values in the previous step but no error is raised if one is missing):

• The global defaults are stored in the installation directory.
• The user default are stored in ~/.brian/user_preferences (which works on Windows as well as Linux). The ~ symbol refers to the user directory.
• The file brian_preferences in the current directory.

The preference files are of the following form:

a.b.c = 1
# Comment line
[a]
b.d = 2
[a.b]
b.e = 3

This would set preferences a.b.c=1, a.b.d=2 and a.b.e=3.

List of preferences

Brian itself defines the following preferences (including their default values):