Cascaded Parameters

TL;DR

• Parameters are forwarded through a chain of functions or modules so each step receives the data it needs.
• This pattern supports breaking complex tasks into smaller, reusable components.
• It can increase coupling and make tracking or debugging errors harder without careful design.

Definition

Cascaded parameters refer to the process of passing parameters or values from one function or module to another, creating a chain or cascade of dependencies.

Explanation

Cascaded parameters are commonly used to decompose complex tasks into smaller, more manageable pieces and to enable code reusability. In this pattern, a top-level function or module supplies parameters to subordinate functions or modules. Those subordinate units may in turn pass outputs and/or parameters to additional units, forming a cascade of dependencies. The final outputs produced by lower-level functions are then returned up the chain to the caller, which uses them to produce the overall result.

Examples

Shopping cart total

A function that calculates the total cost of a shopping cart might take parameters such as the price of each item, the quantity of each item, and any applicable discounts or taxes. To compute the total, the function could call several other functions or modules: a function to calculate the subtotal of the items, a function to apply discounts, and a function to apply taxes. Each of these functions requires its own set of parameters, which are passed down from the main function, creating a cascade of dependencies. The main function would pass its parameters to the subtotal function, which would then pass its output to the discount function, and so on. The final output of the tax function would then be passed back up the chain to the main function, where it would be used to calculate the final total cost.

Web application product list

A web application that displays a list of products might have the main page call a function or module to retrieve the list of products from a database. That function would require parameters such as the category and sorting options for the products. The main page might also call a function to format the product list for display, which would require parameters such as the layout and styling options. In this case, the main page would be the first in the cascade, passing its parameters to the database function, which would then pass its output to the formatting function. The final output of the formatting function would then be passed back up the chain to the main page for display.

Notes or pitfalls

• Cascaded parameters can improve modularity and maintainability by separating complex tasks into smaller components.
• They enable greater code reusability, since individual functions or modules can be reused with different parameter sets.
• Cascaded parameters can create complex dependencies and make it difficult to track and debug errors; careful planning and design are necessary to manage these drawbacks.

Related terms

• Function
• Module
• Dependency
• Modularity
• Reusability