macro: Create, modify or remove a global variable or function

In sdbuildR: Easily Build, Simulate, and Visualise Stock-and-Flow Models

Create, modify or remove a global variable or function

Description

Macros are global variables or functions that can be used throughout your stock-and-flow model. macro() adds, changes, or erases a macro.

Usage

macro(sfm, name, eqn = "0.0", doc = "", change_name = NULL, erase = FALSE)

Arguments

sfm	Stock-and-flow model, object of class sdbuildR_xmile.
name	Name of the macro. The equation will be assigned to this name.
eqn	Equation of the macro. A character vector. Defaults to "0.0".
doc	Documentation of the macro. Defaults to "".
change_name	New name for macro (optional). Defaults to NULL to indicate no change.
erase	If TRUE, remove macro from the model. Defaults to FALSE.

Value

A stock-and-flow model object of class sdbuildR_xmile

Examples

# Simple function
sfm <- xmile() |>
  macro("double", eqn = "function(x) x * 2") |>
  build("a", "constant", eqn = "double(2)")

# Function with defaults
sfm <- xmile() |>
  macro("scale", eqn = "function(x, factor = 10) x * factor") |>
  build("b", "constant", eqn = "scale(2)")

# If the logistic() function did not exist, you could create it yourself:
sfm <- macro(xmile(), "func", eqn = "function(x, slope = 1, midpoint = .5){
   1 / (1 + exp(-slope*(x-midpoint)))
 }") |>
  build("c", "constant", eqn = "func(2, slope = 50)")

sdbuildR documentation built on Nov. 19, 2025, 5:07 p.m.