supply-demand

A Python library for dependency orchestration and “demand/supply” resolution (function DI).
Inspired by advanced dependency-injection/inversion control, it lets you register “supplier” functions by key/type, and lets any supplier demand values from others—allowing composition, overrides, and dependency graphs.

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Features

• Register “suppliers” (functions) for different types/keys
• Compose suppliers & override them dynamically
• Pass context (scope) through demands
• Supports both, async and sync suppliers
• Auto-manages dependency graph and supplier registry merging

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Installation

pip install supply-demand

or

python -m pip install supply-demand

or

python3 -m pip install supply-demand

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Quick Start

from supply_demand import supply_demand
import asyncio

async def value_supplier(data, scope):
    return 42

async def root_supplier(data, scope):
    answer = await scope.demand({"type": "value"})
    print("Supply chain returned:", answer)

suppliers = {"value": value_supplier}
asyncio.run(supply_demand(root_supplier, suppliers))

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Example: Dependency Chain

async def A(data, scope):
    return 1

async def B(data, scope):
    a_val = await scope.demand({"type": "A"})
    return a_val + 5

async def root(data, scope):
    result = await scope.demand({"type": "B"})
    print("Result:", result)

suppliers = {"A": A, "B": B}
asyncio.run(supply_demand(root, suppliers))

Output: Result: 6

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API

supply_demand(root_supplier, suppliers)

• root_supplier: Callable (data, scope). The entry point.
• suppliers: Dict of {type: supplier_func, ...}.

context.demand(props)

• props["type"] — The supplier type to demand.
• Can override suppliers, pass data, etc.

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Advanced

Supports registry extension, override, additive/clear logic via:

scope.demand({
  "type": "X",
  "suppliers": {"add": {"X": custom_x_supplier}}
})

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License

MIT