Henrik Lemke
98d8e4a0c5
- docs/did_you_know/: one short tip per feature added since May 2026 (<date>-<slug>.md, YAML front matter: added/tags/details), listed newest first; index.md describes the format for adding more. - New pages for features that had none: launching, command_history, tab_completion, live_gui, tweak, scanning, status_server, channel_access, shared_files, schematic_panels. Wired into index.rst together with the existing queues page. - Fix archiver_stripchart/listening_monitor: the method is archiver.strip_plot (strip_chart does not exist on DataHub); document the per-device .strip_plot(). - NAMESPACE_MONITOR_FORMAT.md: scan monitoring is wired into Daq's scan callbacks since 2026-09-09. - scripts/eco-docs (+ -install-user-service): build the docs from an own clone and serve them over HTTP as user systemd units, rebuilt by a timer; a failed build never replaces the served site.
41 lines
1.7 KiB
Markdown
41 lines
1.7 KiB
Markdown
# Tab completion on lazy devices
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Most components in the Bernina namespace are **lazy**: they are only built
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(with real EPICS connections) the first time you use them. Tab completion has
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to look inside a device to list its children, so without care, pressing Tab
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would quietly build devices you never meant to touch.
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## Two Tabs to initialize
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If the device you are completing into has not been initialized yet, the first
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Tab does nothing except tell you so:
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```text
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In [1]: prepump.<TAB>
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eco: 'prepump' is not initialized yet -- press Tab again to initialize it and complete.
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In [1]: prepump.<TAB>
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check gp isolate_all line1_usd line2_lic pump_down roots_pump show vent ...
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```
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The second Tab initializes it and completes as usual. This works at any depth
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(`bernina.something.<TAB>`) and still counts if you kept typing between the
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two Tabs.
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Only the one component named in the expression is ever initialized, never
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its siblings that happen to share a prefix. Completing into a device that is
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already initialized works on the first Tab, as before.
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## What makes completion work on eco objects
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You normally don't need to know this, but if completion breaks after an
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IPython upgrade, these are the three settings involved. eco sets them in every
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session it starts (terminal, desktop console, `start_console()`):
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1. `Completer.use_jedi = False`. jedi resolves every candidate to inspect it,
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which on a lazy namespace means initializing everything with a matching
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prefix. It also returns no matches at all on eco's dynamic objects.
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2. eco's lazy-proxy class is allow-listed in IPython's `guarded_eval` policy.
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Without it, completing two levels deep (`prepump.line1_usd.<TAB>`) silently
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returns nothing.
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3. The two-Tab gate described above.
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