`Instr._repr_html_` Test Notebook¶

This notebook builds an example instrument that exercises:

DECLARE / INITIALIZE / SAVE / FINALLY C code blocks (collapsible via <details>)
Instrument parameters
Multiple component instances in the TRACE section (collapsible list)
A metadata group
An InMemoryRegistry (custom in-memory component definitions)
A RemoteRegistry reference (displayed with clickable URL)

The last cell puts the Instr object on its own line so Jupyter calls _repr_html_ automatically.

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from mccode_antlr.assembler import Assembler
from mccode_antlr.reader.registry import InMemoryRegistry
from mccode_antlr import Flavor
from mccode_antlr.assembler import Assembler
from mccode_antlr.reader.registry import InMemoryRegistry
from mccode_antlr import Flavor

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# A minimal in-memory component so we don't need an external registry
simple_detector = """
DEFINE COMPONENT SimpleDetector
DEFINITION PARAMETERS ()
SETTING PARAMETERS (xwidth=0.1, yheight=0.1, string filename="det.dat")
OUTPUT PARAMETERS ()
SHARE
%{
%}
DECLARE
%{
  double counts;
%}
INITIALIZE
%{
  counts = 0;
%}
TRACE
%{
  SCATTER;
  counts += 1;
%}
SAVE
%{
  DETECTOR_OUT_2D("SimpleDetector", "X", "Y", -xwidth/2, xwidth/2,
                  -yheight/2, yheight/2, 100, 100, NULL, filename);
%}
FINALLY
%{
%}
END
"""

mem_registry = InMemoryRegistry('custom', SimpleDetector=simple_detector)
# A minimal in-memory component so we don't need an external registry
simple_detector = """
DEFINE COMPONENT SimpleDetector
DEFINITION PARAMETERS ()
SETTING PARAMETERS (xwidth=0.1, yheight=0.1, string filename="det.dat")
OUTPUT PARAMETERS ()
SHARE
%{
%}
DECLARE
%{
  double counts;
%}
INITIALIZE
%{
  counts = 0;
%}
TRACE
%{
  SCATTER;
  counts += 1;
%}
SAVE
%{
  DETECTOR_OUT_2D("SimpleDetector", "X", "Y", -xwidth/2, xwidth/2,
                  -yheight/2, yheight/2, 100, 100, NULL, filename);
%}
FINALLY
%{
%}
END
"""

mem_registry = InMemoryRegistry('custom', SimpleDetector=simple_detector)

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a = Assembler('example_instrument', flavor=Flavor.MCSTAS)

# Give the assembler access to our custom in-memory component
a.reader.registries.append(mem_registry)

# Instrument parameters
a.parameter('double E0 = 10')
a.parameter('double dE = 1')
a.parameter('double dist = 10')

# DECLARE block
a.declare('double v0;  /* neutron speed at source */')

# INITIALIZE block
a.initialize('v0 = SE2V * sqrt(E0);  /* SE2V converts meV to m/s */')

# SAVE block
a.save('fprintf(stdout, "Run complete. E0=%g meV\\n", E0);')

# Metadata group
a.metadata('instrument_info', 'text/plain',
           'Example instrument for testing mccode-antlr HTML output.\nBuilt programmatically with Assembler.')

# TRACE: component instances
origin = a.component('origin', 'Progress_bar', at=[0, 0, 0])

source = a.component(
    'source', 'Source_simple',
    at=([0, 0, 0], origin),
    parameters={
        'radius': 0.05,
        'yheight': 0,
        'xwidth': 0,
        'dist': 'dist',
        'focus_xw': 0.05,
        'focus_yh': 0.05,
        'E0': 'E0',
        'dE': 'dE',
    },
)

guide = a.component(
    'guide', 'Guide_gravity',
    at=([0, 0, 2], source),
    parameters={
        'w1': 0.05,
        'h1': 0.05,
        'w2': 0.03,
        'h2': 0.03,
        'l': 10,
        'm': 3.5,
    },
)

slit = a.component(
    'slit', 'Slit',
    at=([0, 0, 0.1], guide),
    parameters={'xwidth': 0.02, 'yheight': 0.02},
)

sample = a.component(
    'sample', 'V_sample',
    at=([0, 0, 1], slit),
    parameters={
        'radius': 0.005,
        'yheight': 0.05,
        'focus_r': 0.3,
        'target_index': 1,
    },
)

# Use our custom in-memory component
detector = a.component(
    'detector', 'SimpleDetector',
    at=([0, 0, 0.5], sample),
    parameters={'xwidth': 0.3, 'yheight': 0.3, 'filename': '"psd.dat"'},
)

instr = a.instrument
a = Assembler('example_instrument', flavor=Flavor.MCSTAS)

# Give the assembler access to our custom in-memory component
a.reader.registries.append(mem_registry)

# Instrument parameters
a.parameter('double E0 = 10')
a.parameter('double dE = 1')
a.parameter('double dist = 10')

# DECLARE block
a.declare('double v0;  /* neutron speed at source */')

# INITIALIZE block
a.initialize('v0 = SE2V * sqrt(E0);  /* SE2V converts meV to m/s */')

# SAVE block
a.save('fprintf(stdout, "Run complete. E0=%g meV\\n", E0);')

# Metadata group
a.metadata('instrument_info', 'text/plain',
           'Example instrument for testing mccode-antlr HTML output.\nBuilt programmatically with Assembler.')

# TRACE: component instances
origin = a.component('origin', 'Progress_bar', at=[0, 0, 0])

source = a.component(
    'source', 'Source_simple',
    at=([0, 0, 0], origin),
    parameters={
        'radius': 0.05,
        'yheight': 0,
        'xwidth': 0,
        'dist': 'dist',
        'focus_xw': 0.05,
        'focus_yh': 0.05,
        'E0': 'E0',
        'dE': 'dE',
    },
)

guide = a.component(
    'guide', 'Guide_gravity',
    at=([0, 0, 2], source),
    parameters={
        'w1': 0.05,
        'h1': 0.05,
        'w2': 0.03,
        'h2': 0.03,
        'l': 10,
        'm': 3.5,
    },
)

slit = a.component(
    'slit', 'Slit',
    at=([0, 0, 0.1], guide),
    parameters={'xwidth': 0.02, 'yheight': 0.02},
)

sample = a.component(
    'sample', 'V_sample',
    at=([0, 0, 1], slit),
    parameters={
        'radius': 0.005,
        'yheight': 0.05,
        'focus_r': 0.3,
        'target_index': 1,
    },
)

# Use our custom in-memory component
detector = a.component(
    'detector', 'SimpleDetector',
    at=([0, 0, 0.5], sample),
    parameters={'xwidth': 0.3, 'yheight': 0.3, 'filename': '"psd.dat"'},
)

instr = a.instrument

2026-03-05 15:11:11.844 | DEBUG    | mccode_antlr.reader.reader:add_component:243 - Component cache hit: /home/g/.cache/mccodeantlr/mcstas/v3.5.31/mcstas-comps/misc/Progress_bar.comp
2026-03-05 15:11:11.858 | DEBUG    | mccode_antlr.reader.reader:add_component:243 - Component cache hit: /home/g/.cache/mccodeantlr/mcstas/v3.5.31/mcstas-comps/sources/Source_simple.comp
2026-03-05 15:11:11.864 | DEBUG    | mccode_antlr.reader.reader:add_component:243 - Component cache hit: /home/g/.cache/mccodeantlr/mcstas/v3.5.31/mcstas-comps/optics/Guide_gravity.comp
2026-03-05 15:11:11.869 | DEBUG    | mccode_antlr.reader.reader:add_component:243 - Component cache hit: /home/g/.cache/mccodeantlr/mcstas/v3.5.31/mcstas-comps/optics/Slit.comp
2026-03-05 15:11:11.874 | DEBUG    | mccode_antlr.reader.reader:add_component:243 - Component cache hit: /home/g/.cache/mccodeantlr/mcstas/v3.5.31/mcstas-comps/obsolete/V_sample.comp

Display the instrument¶

Placing instr on the last line of a code cell triggers Jupyter's rich display — it calls _repr_html_() automatically.

Expect to see:

DECLARE, INITIALIZE, SAVE code blocks collapsed under <details> (click to expand)
TRACE section as a collapsible open list of components
Registry headers with clickable links (for remote registries)
InMemoryRegistry: custom (1 components) label for the in-memory registry

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instr
instr

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Instrument example_instrument

Instrument: example_instrument
Source: interactive
Contains:
Registries: libc mcstas custom
Registry: libc https://github.com/mccode-dev/McCode v3.5.31 libc-registry.txt https://github.com/mccode-dev/mccode-pooch-registries
Registry: mcstas https://github.com/mccode-dev/McCode v3.5.31 mcstas-registry.txt https://github.com/mccode-dev/mccode-pooch-registries
InMemoryRegistry: custom (1 components)

DEFINE INSTRUMENT example_instrument(

…

E0=10, dE=1, dist=10

)
METADATA text/plain instrument_info

…

Example instrument for testing mccode-antlr HTML output.
Built programmatically with Assembler.

DECLARE

double v0;  /* neutron speed at source */

INITIALIZE

v0 = SE2V * sqrt(E0);  /* SE2V converts meV to m/s */

TRACE

COMPONENT origin = Progress_bar() AT (0, 0, 0) ABSOLUTE
COMPONENT source = Source_simple(
…
radius=0.05, yheight=0, xwidth=0, dist=dist, focus_xw=0.05, focus_yh=0.05, E0=E0, dE=dE
) AT (0, 0, 0) RELATIVE origin ROTATED (0.0, 0.0, 0.0) RELATIVE origin
COMPONENT guide = Guide_gravity(
…
w1=0.05, h1=0.05, w2=0.03, h2=0.03, l=10, m=3.5
) AT (0, 0, 2) RELATIVE source ROTATED (0.0, 0.0, 0.0) RELATIVE source
COMPONENT slit = Slit(
…
xwidth=0.02, yheight=0.02
) AT (0, 0, 0.1) RELATIVE guide ROTATED (0.0, 0.0, 0.0) RELATIVE guide
COMPONENT sample = V_sample(
…
radius=0.005, yheight=0.05, focus_r=0.3, target_index=1
) AT (0, 0, 1) RELATIVE slit ROTATED (0.0, 0.0, 0.0) RELATIVE slit
COMPONENT detector = SimpleDetector(
…
xwidth=0.3, yheight=0.3, filename="psd.dat"
) AT (0, 0, 0.5) RELATIVE sample ROTATED (0.0, 0.0, 0.0) RELATIVE sample

SAVE

fprintf(stdout, "Run complete. E0=%g meV\n", E0);

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Instr._repr_html_ Test Notebook¶

Display the instrument¶

`Instr._repr_html_` Test Notebook¶