Migration Guide: v1.4.0 → v1.5.0

InputConfig API Simplification

Version 1.5.0 simplifies the InputConfig constructor by eliminating the redundant count parameter. The number of inputs is now automatically deduced from the template arguments, making the API cleaner and less error-prone.

Breaking Change: `count` Parameter Removed

What Changed

The InputConfig constructor no longer requires the explicit count argument. The number of inputs is automatically deduced from the template variadic arguments.

Before

cpp

pr32::input::InputConfig inputConfig(
    6,              // count - now auto-deduced
    BTN_UP,
    BTN_DOWN,
    BTN_LEFT,
    BTN_RIGHT,
    BTN_A,
    BTN_B
);

After

cpp

pr32::input::InputConfig inputConfig(
    BTN_UP,
    BTN_DOWN,
    BTN_LEFT,
    BTN_RIGHT,
    BTN_A,
    BTN_B
);

Memory Optimization: `std::vector` → `std::array`

Why This Change

Version 1.5.0 replaces std::vector with std::array in InputConfig:

Aspect	Before (`std::vector`)	After (`std::array`)
Heap allocation	Yes (dynamic)	No (stack/global)
Fragmentation	Possible	None
Determinism	Non-deterministic	O(1) access
Max inputs	Dynamic (runtime)	Fixed (16)
Zero-init	Required manually	Automatic via `{}`

Memory Impact

Metric	Before	After
`InputConfig` size	~24 bytes (heap)	72 bytes (stack, fixed)
ESP32 heap usage	Variable	0 bytes
Allocation at runtime	Yes	None

API Changes

Constructor Signature

Before:

cpp

InputConfig(int count, ...);  // variadic with explicit count

After:

cpp

template<typename... Args>
InputConfig(Args... args);  // count auto-deduced

Empty Configuration

Before:

cpp

InputConfig config(0);  // empty with count

After:

cpp

InputConfig config{};  // default constructor or empty init list
InputConfig config();  // also valid

Migration Patterns

Pattern 1: Remove the Count Parameter

cpp

// Before
pr32::input::InputConfig config(4, PIN_1, PIN_2, PIN_3, PIN_4);

// After
pr32::input::InputConfig config(PIN_1, PIN_2, PIN_3, PIN_4);

Pattern 2: Empty Configuration

cpp

// Before
pr32::input::InputConfig config(0);

// After
pr32::input::InputConfig config{};
// or
pr32::input::InputConfig config;

Pattern 3: Single Input

cpp

// Before
pr32::input::InputConfig config(1, BTN_UP);

// After
pr32::input::InputConfig config(BTN_UP);

Pattern 4: Native Platform (SDL2)

cpp

// Before
pr32::input::InputConfig config(2, SDL_SCANCODE_UP, SDL_SCANCODE_DOWN);

// After
pr32::input::InputConfig config(SDL_SCANCODE_UP, SDL_SCANCODE_DOWN);

Compile-Time Validation

The new implementation includes compile-time validation:

Overflow Detection

cpp

// If more than 16 arguments are passed, compilation fails:
InputConfig config(1, 2, 3, ..., 17);  // static_assert error at compile time

Error Message

error: static_assert failed due to requirement 'sizeof...(Args) <= MAX_INPUT_COUNT'
"Too many arguments for InputConfig"

Runtime Validation

Invalid configurations are handled at runtime:

Scenario	Behavior
Empty config	`count = 0`, arrays zero-initialized
1-16 inputs	`count = N`, valid
>16 inputs	`count = 16` (clamped)

Migration Checklist

[ ] Search for InputConfig( calls: Find all usages with explicit count
[ ] Remove the first integer argument: The count is now automatic
[ ] Verify count deduction: Ensure the new count matches expected
[ ] Check empty configurations: Replace InputConfig(0) with InputConfig{}
[ ] Build and test: Ensure all scenes compile and run correctly

Search Patterns

bash

# Find all InputConfig usages
grep -rn "InputConfig(" --include="*.cpp" --include="*.h"

# Specific pattern for explicit count (regex)
InputConfig\([0-9]+,

Backward Compatibility

This is a breaking change. The old constructor signature InputConfig(int count, ...) no longer works.

If you have code like this:

cpp

InputConfig config(3, A, B, C);  // OLD API - WILL NOT COMPILE

You must update to:

cpp

InputConfig config(A, B, C);  // NEW API

Verification

After migration, verify:

[ ] All InputConfig calls compile without errors
[ ] Input count matches the number of arguments provided
[ ] ESP32 builds succeed with no heap allocation warnings
[ ] Native (SDL2) builds work correctly
[ ] All unit tests pass (pio test -e native_test)

File Changes

This change affects the following files:

File	Change
`include/input/InputConfig.h`	`std::vector` → `std::array`, template variadic constructor
`src/core/Engine.cpp`	Updated `InputConfig(0)` → `InputConfig{}`
All game scenes	Remove `count` parameter from `InputConfig` calls

Migration Guide: v1.4.0 → v1.5.0 ​

InputConfig API Simplification ​

Breaking Change: count Parameter Removed ​

What Changed ​

Before ​

After ​

Memory Optimization: std::vector → std::array ​

Why This Change ​

Memory Impact ​

API Changes ​

Constructor Signature ​

Empty Configuration ​

Migration Patterns ​

Pattern 1: Remove the Count Parameter ​

Pattern 2: Empty Configuration ​

Pattern 3: Single Input ​

Pattern 4: Native Platform (SDL2) ​

Compile-Time Validation ​

Overflow Detection ​

Error Message ​

Runtime Validation ​

Migration Checklist ​

Search Patterns ​

Backward Compatibility ​

Verification ​

File Changes ​

References ​