wend.anchors¶
Anchors: the standard places a path starts from, read from the environment only when asked.
Each anchor is an Absolute parameter named after its environment variable,
so an expression built on one stays symbolic, portable and matchable::
from wend import anchors
from wend.anchors import XDG
models = (P("models") / Param("name")).under(XDG.CACHE_HOME / "myapp")
models # PathExpr('{XDG_CACHE_HOME}/myapp/models/{name}')
models.render(anchors.bindings(), name="bert") # reads the environment now
render stays pure: nothing here is read until bindings is called, and a
test binds the anchors like any parameter (XDG_CACHE_HOME="/tmp/c").
The XDG directories follow the XDG Base Directory specification on every
POSIX platform, macOS included: the variable when it is set to an absolute
path, otherwise the specification's default below the home directory. For
platform conventions instead (~/Library/Caches on macOS), bind the anchor
to what a library such as platformdirs reports.
module-attribute
¶
The process's working directory, os.getcwd() (not $PWD).
module-attribute
¶
The user's home directory: $HOME, else the password database.
XDG()
The XDG base directories (anchors, not values): XDG.CACHE_HOME /
"myapp" is {XDG_CACHE_HOME}/myapp.
class-attribute
instance-attribute
¶
User configuration: $XDG_CONFIG_HOME, else ~/.config.
class-attribute
instance-attribute
¶
User data: $XDG_DATA_HOME, else ~/.local/share.
class-attribute
instance-attribute
¶
User state (logs, history): $XDG_STATE_HOME, else ~/.local/state.
Every anchor's value, read now: an effect, unlike render.
environ defaults to os.environ. A variable that is unset, empty or
relative falls back to its default, as the XDG specification requires.
CWD is os.getcwd(), and is left out if the working directory no
longer exists, so only an expression that uses it fails to render.