Global Defaults — `dm.config`¶

dm.config is the process-wide singleton that holds dartwork-mpl’s behaviour toggles. Set it once near the top of your program (or in a notebook’s first cell) and every subsequent call across dm.layout, dm.io, and friends honours the new default — no need to thread the keyword through every call site.

Per-call overrides always win. Passing simple_layout(fig, adopt_orphan_tick_font=True) overrides whatever you set on dm.config. The singleton supplies the fallback only.

What’s in there¶

dm.config is a @dataclass with named fields. Today there are two; more land as audit findings ship.

Field	Default	Affects
`adopt_orphan_tick_font`	`True`	`simple_layout`, `save_formats`, `save_and_show` — when an axis has tick labels but no axis label, dartwork copies the axis label font (size + weight + family) onto the ticks so the figure reads as one designed object. Set `False` to leave tick fonts alone.
`warn_on_orphan_tick_adoption`	`False`	Same three call sites. When `True`, emits a one-time `UserWarning` every time the adoption mutates a figure. Useful when debugging surprise tick changes, or when running under matplotlib’s `constrained_layout` where the font swap can trigger a re-layout.

The full surface is in config.py — that’s the SSOT, this page is the cookbook.

Patterns¶

1. Flip a default project-wide¶

Set once near the top of your entry script or notebook. Every simple_layout / save_formats / save_and_show call afterwards picks it up.

import matplotlib.pyplot as plt
import dartwork_mpl as dm

# This project prefers tick fonts left untouched.
dm.config.adopt_orphan_tick_font = False

dm.style.use("scientific")

fig, ax = plt.subplots(figsize=dm.figsize("13cm", "standard"))
ax.plot([1, 2, 3], [1, 4, 9])

dm.simple_layout(fig)          # tick fonts NOT adopted (config wins)
dm.save_formats(fig, "out", formats=("png", "svg"))

2. Scope the change to a `with` block¶

dm.config.override(...) restores the previous values on exit, even on exception. Use this when most of your code wants the default but one specific export needs the opposite.

dm.config.adopt_orphan_tick_font = False     # default: off

with dm.config.override(adopt_orphan_tick_font=True):
    dm.simple_layout(fig)                    # adoption ON here
    dm.save_formats(fig, "press_release", formats=("pdf",))

dm.simple_layout(fig)                        # back to OFF

The block is exception-safe — raising inside still restores every overridden field.

3. Per-call override beats config¶

Pass the keyword explicitly when you want to bypass dm.config for a single call. Anything you pass (True or False) wins; the only value that defers to dm.config is None (the call-site default).

dm.config.adopt_orphan_tick_font = True      # project default

# Just this figure: skip adoption.
dm.simple_layout(fig, adopt_orphan_tick_font=False)

4. Debug surprise tick changes¶

When a tick font silently changes between two draws (a common constrained-layout / re-layout hazard), turn the warning on. Every adoption emits a UserWarning that includes the axis it touched, so you can isolate the offender.

import warnings

dm.config.warn_on_orphan_tick_adoption = True

with warnings.catch_warnings(record=True) as caught:
    warnings.simplefilter("always")
    dm.simple_layout(fig)

for w in caught:
    print(w.message)
# UserWarning: orphan-tick font adoption mutated 2 axes ...

Pair with dm.config.adopt_orphan_tick_font = False and the warning goes silent — confirming you’ve fully opted out.

5. Typos fail loudly¶

override(...) raises AttributeError for any field name that isn’t declared on Config. A typo can’t silently shadow the singleton.

try:
    with dm.config.override(adopt_orphn_tick_font=False):   # typo
        ...
except AttributeError as exc:
    print(exc)
# dm.config has no attribute(s): ['adopt_orphn_tick_font']. Known fields: ...

Use this to your advantage: when you suspect a stale doc, just try the field name — if it fails, the field’s gone or never existed.

Mental model¶

        flowchart TD
    A["<b>① per-call keyword</b><br/><code>simple_layout(fig, adopt_orphan_tick_font=False)</code><br/><i>highest priority — always wins</i>"]
    B["<b>② dm.config field</b><br/><code>dm.config.adopt_orphan_tick_font = False</code><br/><i>project-wide default</i>"]
    C["<b>③ hard-coded Config default</b><br/><code>True</code><br/><i>library fallback</i>"]
    A -->|"keyword is None → fall through"| B
    B -->|"field unset → fall through"| C

    style A fill:#fef3c7,stroke:#f0c000,stroke-width:1.5px,color:#1c2024
    style B fill:#ecfeff,stroke:#7cd4e0,stroke-width:1px,color:#1c2024
    style C fill:#f3e8ff,stroke:#c4a0e8,stroke-width:1px,color:#1c2024

The chain is deterministic and read-only at the lower levels — the per-call keyword never mutates dm.config, and dm.config never mutates the dataclass defaults.

When to add a new field¶

For library contributors — most users can skip this section; it’s about proposing a new dm.config field, not using the existing ones.

Don’t reach for dm.config for everything. Use it when:

The toggle is a bool / enum default the user might want to flip for a whole project, not a per-call decision.
There’s no preset-level home for it (preset attributes are for style, dm.config is for behaviour).
The current default is silent — i.e., users today have no knob, and one would help.

Skip it when:

The setting belongs to a preset (dm.style.use(...)).
The setting is truly call-site (file paths, individual figure options).

The roadmap of candidate fields is tracked at issue #311 (B19 — config audit).

Global Defaults — dm.config¶