Code Examples

PME code is most useful when it removes a specific piece of Blender workflow friction. Start with a goal below; use the syntax collection when you need to understand or adapt the command itself.

The archive often uses compact names such as C, L, E, and U. PME Terms You Will Meet explains where each name is available before you copy a snippet into a different slot type.

Choose what you want to build

Make one item respond intelligently

• Choose between a Command branch, Poll, or a live Custom control
• Use Alt, Ctrl, or Shift for different actions
• Route one trigger by mode, selection, or object type

Build automation that stays maintainable

• Run a Macro from a menu or panel item
• Run trusted Python from an external file
• Capture and restore state across Macro steps

Build a control or custom interface

• Bind a PME Property to a Blender value
• Draw editable object dimensions with L.prop()
• Draw an existing Blender panel with panel()

Reflect live state and give feedback

• Show a Blender property’s state on an action button
• Show brief feedback with overlay()
• Redraw the right Blender area after changing data

Diagnose code that works only in some places

• Diagnose operator context and poll failures
• Find imports or state that exist only in the Text Editor session
• Separate a command problem from stale keymap data

Revisit a community technique

These pages preserve useful designs whose historical setup still needs a compatibility test.

• Apply one value, a delta, or a ratio across selected objects
• Give one Macro visible Property options
• Study a context override used to draw a Pose panel in Weight Paint

Focused recipes

Use these after you know which kind of behavior or interface you are building.

Context and availability

• Keep an action disabled until its option is enabled
• Use one hotkey for different Node Editor menus
• Guard a Custom layout against object type and no selection

Calling and integrating automation

• Call a named PME Macro from an external script
• Resize the active Blender area from PME

Custom-layout details

• Draw only X, Y, or Z from a vector property
• Draw an Object, Bone, or Scene custom property
• Draw Blender header menus with header_menu()
• Add a Blender template widget to a Popup Dialog
• Give enum buttons explicit labels

Essential syntax collection

The compact patterns below are retained because PME’s standard Command, Custom, and Poll authoring fields are single-line controls. Use semicolons and expressions for short commands; use an external script when the logic deserves normal multiline Python.

Standard PME command fields use one line

Keep short commands in the field; move longer or reusable logic into a Python file.

• Use ; (semicolon) to separate statements
• Use ternary expressions a if condition else b instead of if/else blocks
• Use list comprehensions [x for x in items] instead of for loops
• Use and/or for short-circuit evaluation instead of conditionals

The multi-line examples in this guide are for readability only. Convert them to a single line before entering them into a standard PME command field.

Converting Multi-Line to Single-Line

Readable format (for documentation):

if bpy.context.mode == 'EDIT_MESH':
    bpy.ops.mesh.select_all(action='SELECT')
else:
    bpy.ops.object.select_all(action='SELECT')

Actual PME format (what you must type):

bpy.ops.mesh.select_all(action='SELECT') if C.mode == 'EDIT_MESH' else bpy.ops.object.select_all(action='SELECT')

Multi-statement example (requires an active object):

# Readable:
obj = C.active_object
obj.show_wire = True
obj.show_all_edges = True
 
# PME format:
obj = C.active_object; obj.show_wire = True; obj.show_all_edges = True

---

Understanding PME Code Slots

PME has several places where you can write Python code:

Location	Purpose	Example
Command slot	Execute operators or short code	bpy.ops.mesh.subdivide()
Custom slot	Draw UI with UILayout	Labels, properties, operators
Poll tab	Gate menu or item visibility	return C.mode == 'EDIT_MESH'
Property editor	Expose a reusable value	Scene/object settings

PME Global Variables

PME provides shorthand variables for common Blender modules:

Variable	Equivalent	Description
C	bpy.context	Current context
D	bpy.data	Blender data
O	bpy.ops	Operators
T	bpy.types	Type definitions
L	UILayout	Current layout (Custom slot)
E	Event	Current scoped event, when available
U	UserData	Session-scoped scratch data

---

Basic Patterns

Simple Operator Call

O.mesh.subdivide(number_cuts=2)

Multiple Operations (Macro-style)

# Readable:
bpy.ops.object.duplicate()
bpy.ops.transform.translate(value=(1, 0, 0))
 
# PME format:
O.object.duplicate(); O.transform.translate(value=(1, 0, 0))

Conditional Execution (Ternary)

# Instead of if/else blocks, use ternary:
O.mesh.select_all(action='SELECT') if C.mode == 'EDIT_MESH' else O.object.select_all(action='SELECT')

Short-Circuit Evaluation

Use and/or for conditional execution:

# Execute only in a valid object context:
C.mode == 'OBJECT' and C.active_object and O.object.shade_smooth()
 
# Execute with fallback:
C.selected_objects or message_box("No objects selected!")

---

Common Recipes

Toggle Selection Mode

# Readable version:
ts = C.tool_settings
mode = tuple(ts.mesh_select_mode)
if mode == (True, False, False):
    ts.mesh_select_mode = (False, True, False)
elif mode == (False, True, False):
    ts.mesh_select_mode = (False, False, True)
else:
    ts.mesh_select_mode = (True, False, False)
 
# PME format (using nested ternary):
ts = C.tool_settings; m = tuple(ts.mesh_select_mode); ts.mesh_select_mode = (False, True, False) if m == (True, False, False) else ((False, False, True) if m == (False, True, False) else (True, False, False))

Access Active Object Properties

# Readable:
obj = C.active_object
if obj is not None:
    obj.show_wire = not obj.show_wire
 
# PME format:
obj = C.active_object; obj is not None and setattr(obj, "show_wire", not obj.show_wire)

Undo Boundaries for Multi-Step Actions

Undo behavior varies by operator, mode, and Blender version. Test the sequence before adding a manual undo push; Plan undo boundaries for multi-step PME actions explains the historical observation and test procedure.

---

Running External Python Files

Call External Script

If you need to run a .py file, use the execute_script() function. This is essential for complex scripts that cannot fit in a single line.

execute_script() Function

execute_script(path, **kwargs)

• path: A scripts/... path checks the user scripts directory first and then PME’s bundled scripts; other relative paths use the add-on directory, and absolute paths are accepted
• kwargs: Additional keyword arguments passed to the script
• Returns: Value of return_value variable in script, or True by default

Usage Examples

Basic execution:

execute_script("scripts/my_script.py")

With parameters:

execute_script("scripts/my_script.py", msg="Hello World!", count=5)

Inside your script (my_script.py):

# Access passed parameters via kwargs
msg = kwargs.get("msg", "Default")
count = kwargs.get("count", 1)
 
# PME globals are available (C, D, O, L, etc.)
for i in range(count):
    print(msg)
 
# Return a value
return_value = "Success!"

Available in script:

• PME globals for the current execution context (C, D, O, L, U, and E when a scoped event exists)
• kwargs - Passed keyword arguments
• __file__ - Script file path
• return_value - Set this to return a value

---

Poll Function Examples

Poll functions determine when a menu or slot is visible. They must return a boolean.

Only in Edit Mode

return C.mode == 'EDIT_MESH'

Only When Object Selected

return C.active_object is not None

Only for Mesh Objects

return C.active_object and C.active_object.type == 'MESH'

Multiple Conditions

obj = C.active_object; return obj and obj.type == 'MESH' and C.mode == 'EDIT_MESH'

---

Advanced Patterns

Using the Layout API (Custom Slots)

# Each line separated by ; in actual PME:
L.label(text="My Custom Tool"); L.prop(C.active_object, "name"); L.operator("mesh.subdivide"); L.separator(); L.prop(C.scene.render, "engine")

Generate UI Rows with a List Comprehension

# Draw one row for each selected object:
[L.label(text=obj.name, icon='OBJECT_DATA') for obj in C.selected_objects]

Accessing Addon Preferences

prefs = C.preferences.addons['my_addon'].preferences; value = prefs.my_property

Using UserData (U) for Session-Scoped Scratch State

U is a scratch container shared by PME commands during one registered session. Disabling PME or restarting Blender recreates it. Use a PME Property or Blender data when the value must persist.

# Store data for the current PME session:
U.my_value = 42; U.update(foo="bar", count=10)
 
# Retrieve data:
value = U.get("my_value", 0)

---

Debugging Tips

Print to Console

print("Debug:", C.active_object)

Message Box for User Feedback

message_box("Operation completed!", icon='INFO')

Check Available Properties

In Blender’s Python Console:

dir(bpy.context.active_object)

Find Operator ID

1. Open Edit → Preferences → Interface
2. Enable “Developer Extras”
3. Right-click any button → “Edit Source” or hover to see operator ID

---

Quick Reference Card

Pattern	PME Syntax
Multiple statements	stmt1; stmt2; stmt3
If/else	a if cond else b
If only	cond and action
Loop	[action for x in items]
Get with default	obj.get("key", default)
Safe attribute	getattr(obj, "attr", None)
External script	execute_script("path.py", **kwargs)

---

Where next

• Curated scripting answers
• Examples and reusable design patterns
• Explore PME by capability

Search practical answers

Search all 5,599 forum posts

External references

• Blender Python API Docs
• PME scripting documentation