BDSim(load=False) + sim.blockdiagram() raises AssertionError, defeating the point of load=False

[petercorke]

BDSim(load=False) is documented (see Coding-patterns) as the way to construct a block diagram without dynamically loading the block library, and instead build it from block classes imported directly (from bdsim.blocks import Step, Gain, ...) with bd=bd passed to each constructor.

In practice, sim.blockdiagram() unconditionally asserts the block library exists, even when load=False was explicitly passed to skip loading it:

https://github.com/petercorke/bdsim/blob/main/src/bdsim/run_sim.py#L2124

import bdsim

sim = bdsim.BDSim(load=False)
bd = sim.blockdiagram()   # AssertionError

sim.blockdiagram() needs the block library only to bind the upper-case factory methods (.GAIN, .STEP, etc.) onto the returned BlockDiagram — methods the "non factory" pattern deliberately doesn't use. The assert fires regardless, defeating the point of load=False.

Workaround (used to keep the wiki's Coding-patterns page accurate): construct BlockDiagram directly, bypassing sim.blockdiagram(), and set the one attribute it would otherwise have set for you:

from bdsim.blockdiagram import BlockDiagram

bd = BlockDiagram(name="main")
bd.runtime = sim   # normally set inside sim.blockdiagram()

This works, but it's a rough edge — reaching into an attribute that's commented # set by BDSim before compilation shouldn't be necessary for a documented usage pattern.

Suggested fix: in blockdiagram(), skip the factory-method-binding loop (rather than asserting) when self._blocklibrary is None, and set bd.runtime = self either way.

Found while auditing the wiki against current main — the Coding-patterns page's "Non factory" example predates this and was silently broken.